                           PUBLISHED

UNITED STATES COURT OF APPEALS
                FOR THE FOURTH CIRCUIT


JOHN LEE CONAWAY,                      
              Petitioner-Appellant,
                 v.
MARVIN POLK, Warden, Central                    No. 04-20
Prison, Raleigh, North Carolina;
NORTH CAROLINA ATTORNEY
GENERAL,
              Respondents-Appellees.
                                       
            Appeal from the United States District Court
       for the Middle District of North Carolina, at Durham.
                James A. Beaty, Jr., District Judge.
                         (CA-98-1117-1)

                      Argued: October 25, 2005

                       Decided: July 11, 2006

    Before WIDENER, KING, and DUNCAN, Circuit Judges.



Affirmed in part and remanded in part by published opinion. Judge
King wrote the opinion, in which Judge Duncan joined. Judge Wid-
ener wrote a concurring opinion.


                            COUNSEL

ARGUED: Burton Craige, PATTERSON HARKAVY, L.L.P.,
Raleigh, North Carolina, for Appellant. Valerie Blanche Spalding,
NORTH CAROLINA DEPARTMENT OF JUSTICE, Raleigh, North
2                         CONAWAY v. POLK
Carolina, for Appellees. ON BRIEF: F. Marsh Smith, Southern
Pines, North Carolina; Matthew Stiegler, CENTER FOR DEATH
PENALTY LITIGATION, Durham, North Carolina, for Appellant.
Roy Cooper, Attorney General of North Carolina, Raleigh, North Car-
olina, for Appellees.


                             OPINION

KING, Circuit Judge:

   John Lee Conaway appeals from the dismissal of his petition for
federal habeas corpus relief with respect to his North Carolina convic-
tions and sentences, including his two death sentences. On April 1,
2005, we granted Conaway a certificate of appealability (the "COA")
on the two claims he raises on appeal: (1) that his Sixth Amendment
right to an impartial jury was contravened because a trial juror con-
cealed a close familial relationship to a co-defendant who was also a
key prosecution witness (the "Juror Bias claim"); and (2) that, because
Conaway is mentally retarded, his execution is precluded by the
Eighth Amendment, as enunciated in Atkins v. Virginia, 536 U.S. 304
(2002) (the "Atkins claim"). After unsuccessfully pursuing these and
other claims in state court, Conaway filed his federal habeas corpus
petition in the Middle District of North Carolina, where he sought an
evidentiary hearing to prove his underlying allegations. In January
2004, the district court denied Conaway’s request for a hearing and
dismissed the petition. Conaway v. French, No. 98-1117 (M.D.N.C.
Jan. 23, 2004).

   As explained below, the state court’s rejection of the Juror Bias
claim involved an unreasonable application of clearly established fed-
eral law as determined by the Supreme Court, and Conaway’s allega-
tions entitle him to an evidentiary hearing. We therefore remand to
the district court for an evidentiary hearing on the Juror Bias claim,
and we affirm the court’s dismissal of the Atkins claim.

                                  I.

                                  A.

  Conaway was convicted in the Superior Court of Richmond
County, North Carolina, on October 15, 1992, of the first-degree mur-
                          CONAWAY v. POLK                            3
ders of Thomas Weatherford and Paul Callahan, and of several related
offenses. In its opinion denying Conaway relief in his direct appeal,
State v. Conaway, 453 S.E.2d 824 (N.C. 1995), the Supreme Court of
North Carolina summarized the facts underlying Conaway’s convic-
tion, in part, as follows:

       On the evening of 22 August 1991, Thomas Amos
    Weatherford and Paul DeWitt Callahan were in the Pantry
    store located on Highway 177 South in Hamlet, North Caro-
    lina. Weatherford was working as the night-shift clerk. Cal-
    lahan, his roommate, had driven Weatherford to work at
    11:00 p.m. and stayed at the store with him for several hours
    that night.

                                 ***

      The evidence showed that [on the night of August 22,
    1991, Conaway, along with Kelly Harrington, Michael
    McKinnon, and Kevin "Keith" Scott] began to walk around
    the streets of Hamlet. [Conaway] started looking for a car he
    could steal to drive back to Washington, D.C. . . .

       Sometime between 1:30 a.m. and 1:45 a.m. on 23 August
    1991, the four men went to the Pantry . . . . [Conaway] told
    the other men to wait outside while he went into the store
    to get more beer. While inside the Pantry, [Conaway] stole
    $78.00 from the cash register and kidnapped Weatherford
    and Callahan at gunpoint.

       McKinnon, Harrington, and Scott all testified at trial that
    several minutes after [Conaway] left them to go into the
    Pantry, he drove up in a dark-colored car. This car was later
    identified as belonging to Callahan. The two victims were
    in the front seat of the car with [Conaway], who was point-
    ing a gun at them. [Conaway] told McKinnon, Harrington,
    and Scott to get into the car. The three men got into the
    backseat of the car, and [Conaway] drove away from the
    Pantry. . . .

                                 ***
4                         CONAWAY v. POLK
       [According to McKinnon, Harrington, and Scott,] [a]fter
    [Conaway] passed the Coca-Cola plant on Highway 74, he
    stopped the car on the side of the road in an isolated area
    and . . . ordered [Weatherford and Callahan] to get out of the
    car. McKinnon, Harrington, and Scott remained in the car,
    while [Conaway] walked the victims into the woods. McK-
    innon, Harrington, and Scott were unable to see [Conaway]
    once he entered the woods, but they heard two gunshots
    fired several seconds apart. . . . [The four men then drove
    together to Washington, D.C.]

                                 ***

       On 29 August 1991, Army Sergeant Daniel Poe was fly-
    ing his ultralight plane near Hamlet looking for his lost dog.
    He was flying at a height of approximately five hundred feet
    over Highway 74 when he noticed something white on the
    ground in the woods. Poe took a closer look and saw the
    victims’ bodies lying on the ground in the woods about
    eighty-seven feet from Highway 74. . . .

                                 ***

       [Conaway, Harrington, McKinnon, and Scott] arrived in
    Washington, D.C., around 8:00 a.m. on 23 August 1991.
    [Conaway] visited with his brother and stepfather that after-
    noon. . . . Late that afternoon, [Conaway] went to Cam-
    bridge, Maryland, to visit two friends and to see his mother.

       McKinnon, Harrington, and Scott stayed with [Con-
    away]’s brother and with Harrington’s cousin Darlene for
    two nights and then went to Maryland to stay with Harring-
    ton’s brother. The three men returned to Hamlet on or about
    30 August 1991 and confessed their participation in these
    murders to the Hamlet police.

       On 25 August 1991, while standing on the street talking
    to a friend from prison, [Conaway] was arrested in Cam-
    bridge, Maryland. . . . When [Conaway] was searched, a
                           CONAWAY v. POLK                            5
      .25-caliber handgun and six .25-caliber rounds of ammuni-
      tion were found in his possession.

Conaway, 453 S.E.2d at 831-33.1

   On September 30, 1991, Conaway was indicted in Richmond
County on two charges of first-degree murder for the deaths of Calla-
han and Weatherford, and he was returned to North Carolina from
Maryland on February 25, 1992. In early March 1992, Conaway was
further indicted for first-degree kidnapping, robbery with a dangerous
weapon, and larceny, arising from the circumstances surrounding the
deaths of Weatherford and Callahan. Harrington, McKinnon, and
Scott (the "co-defendants") were also indicted in Richmond County
on charges of first-degree murder, kidnapping, robbery, and larceny.
The co-defendants each testified against Conaway, who the prosecu-
tion (the "State") tried alone. After Conaway was convicted, the State
dropped the murder charges against the co-defendants, each of whom
pleaded guilty to first-degree kidnapping and received a twenty-five
year sentence.2

                                  B.

                                   1.

   In October 1992, Conaway was tried for first-degree murder and
the related offenses in the Superior Court of Richmond County. From
  1
     At trial, the evidence showed that Conaway had been arrested in
Maryland on unrelated charges prior to the discovery in North Carolina
of the bodies of Weatherford and Callahan. Conaway, 453 S.E.2d at 833.
At the time of his arrest, Maryland authorities found a key on Conaway
that was determined to belong to Weatherford and Callahan. Id. at 834.
Boyd Bostic, a convicted forger, testified for the prosecution that Con-
away had implicated himself while they were housed together in the
Richmond County Jail in May 1992. Id. At trial, Conaway denied any
responsibility for the murders and asserted that he had never spoken to
Bostic. Id. at 834-36.
   2
     According to records of the North Carolina Department of Correc-
tions, Scott was released from custody in 2000, McKinnon in 2001, and
Harrington in 2002.
6                            CONAWAY v. POLK
October 6, 1992, to October 9, 1992, voir dire was conducted of the
prospective jurors in the venire.3 Among the prospective jurors was
a man named Rannie Waddell, Jr. ("Juror Waddell"), who Conaway
alleges was a double first cousin, once removed, of co-defendant Har-
rington, a key prosecution witness.4

   On the first day of the jury selection proceedings, and with the
venire present, the prosecutor read a list of twenty-six witnesses
expected to testify for the State, including co-defendant Harrington.
The prosecutor then asked various potential jurors if they "kn[e]w"
any of the witnesses or "recognize[d]" any of the names. See, e.g.,
J.A. 187.5 That day, three members of the venire were excused for
cause because they knew various witnesses, including one who
explained that co-defendant Scott was her cousin. See, e.g., id. at 188.

    On the afternoon of October 7, 1992, the second day of the jury
    3
     The Latin word "venire" refers to the panel of citizens from which the
jury for a particular trial is selected, and includes those persons not quali-
fied or not selected for jury service. Black’s Law Dictionary 1590 (8th
ed. 2004). The French term "voir dire" refers to the examination which
the trial court and the lawyers make of prospective jurors in the venire
concerning their suitability to serve as jurors. Id. at 1605.
   4
     Conaway maintains that Juror Waddell and co-defendant Harrington
are "double first cousins, once removed." Appellant’s Br. at 4. The term
"double first cousins" is generally used to refer to persons related in the
following manner: "When two brothers marry two sisters, the children of
these two unions are known as double cousins." Vance Randolph, A
Fourth Ozark Word List, American Speech, Feb. 1933, at 47, 48. Double
first cousins have their four grandparents in common. See id. The term
"once removed" indicates that the related parties are separated by a single
generation. See Webster’s Third New International Dictionary 1921
(1976). Double first cousins, once removed, have the same biological
relationship as an uncle and his nephew. The facts alleged by Conaway
are that co-defendant Harrington’s father and Juror Waddell share three
of their four grandparents. In any event, we use Conaway’s characteriza-
tion of the relationship — "double first cousins, once removed" — to
describe the alleged relationship between Juror Waddell and co-
defendant Harrington.
   5
     Citations to "J.A. ___" refer to the contents of the Joint Appendix
filed by the parties in this appeal.
                           CONAWAY v. POLK                            7
selection proceedings, the prosecutor asked Juror Waddell if he knew
any of the individuals who had repeatedly been identified as potential
State witnesses. J.A. 444. Juror Waddell acknowledged that he was
familiar with the witness list and that he knew one potential witness,
Sheriff Sam Jarrell. Id. Juror Waddell did not, however, acknowledge
knowing or being related to co-defendant Harrington. The prosecutor
asked Juror Waddell whether he, any close friend, or any family
member "had any dealings with the District Attorney’s Office," and
Waddell responded, "No." Id. at 445. The prosecutor further inquired
whether Juror Waddell had formed an opinion about the case, and he
again responded in the negative. Id. at 446. When the prosecutor
asked whether there was "any reason whatsoever, whether I’ve asked
you or not that you could think of that would keep you from being
fair and impartial in this case," Juror Waddell answered, "No, sir." Id.
Juror Waddell acknowledged that he had read about the case in a
newspaper approximately a year earlier, but when Conaway’s lawyer
asked if Juror Waddell had talked about the case with any family
members or friends, or had heard anyone else discussing the matter,
he asserted that he had not. Id. at 457-58. Later that day, while Juror
Waddell was yet present, several other prospective jurors were asked
whether they recognized any of the co-defendants, including Harring-
ton. Juror Waddell remained silent, and he was ultimately selected to
serve on the jury.

  On Saturday, October 10, 1992, after the jury had been selected,
but before it was impaneled, Conaway’s lawyer received an anony-
mous phone call at his office. J.A. 1101f. The caller advised the law-
yer’s secretary that Juror Waddell was Harrington’s cousin, "may be
even [his] first cousin." Id.

                                   2.

   The two-day guilt phase of Conaway’s trial began on Monday,
October 12, 1992, after the jury was impaneled and sworn. Later that
day, Harrington testified for the State and denied any responsibility
for the murders of Weatherford and Callahan. He acknowledged that
he faced the same charges as Conaway, but maintained that the State
had not offered to reduce the charges against him, or made other
promises to him in exchange for his testimony. J.A. 989-90. Harring-
ton admitted that, after the murders of Weatherford and Callahan, he
8                         CONAWAY v. POLK
had spent several days in the Washington, D.C. area with McKinnon
and Scott, and that the three co-defendants had discussed "what [they
were] going to say" about the murders. Id. at 988. According to Har-
rington, they considered blaming the murders on a fictitious man
named "Bro," but later decided to "tell the truth" and implicate Con-
away. Id. Harrington testified that, although he had grown up with co-
defendants Scott and McKinnon, he had met Conaway less than two
months before the murders. Id. at 949-50.6 Harrington asserted that he
decided to testify against Conaway because it was "the right thing for
me to do," but he acknowledged that by so doing, he was "defending
[him]self." Id. at 989-90.

   After the State rested its case, Conaway took the stand in his own
defense. Conaway testified that, on the night of August 22, 1991, in
Hamlet, North Carolina, he loaned his grandmother’s handgun to Har-
rington. Conaway, 453 S.E.2d at 835. Conaway then went alone to his
girlfriend’s apartment in Hamlet, where the couple had an argument
and Conaway soon departed. Id. Conaway did not see the co-
defendants again until they picked him up the next morning. Id. Har-
rington returned the handgun to Conaway while the four men were
driving together from North Carolina to Washington, D.C. Id. Con-
away maintained that he did not learn about the murders of Weather-
ford and Callahan until after his Maryland arrest, and he denied any
knowledge of, or responsibility for, the crimes. Id. at 834.

    The trial evidence essentially presented the jury with a swearing
contest between Conaway, on one side, and his co-defendants, includ-
ing Harrington, on the other. Indeed, in closing argument, the prose-
cutor told the jury that "if you believe what Kelly Harrington told you
. . . [y]ou can convict Mr. Conaway of all the charges. If you believe
Mr. Conaway . . . then you will acquit Mr. Conaway. It’s really sim-
ple." J.A. 1082. On October 15, 1992, the jury returned guilty verdicts
against Conaway on all charges: two for first-degree murder, two for
kidnapping, a single charge of robbery with a dangerous weapon, and
one larceny offense. The court then recessed until the following Mon-
    6
   Co-defendants Harrington, McKinnon and Scott all grew up together
around Hamlet, North Carolina. Conaway spent most of his youth in the
Washington, D.C. area.
                          CONAWAY v. POLK                            9
day, October 19, 1992, when the sentencing phase of the trial was to
begin.

                                  3.

   When the proceedings resumed on October 19, 1992, Conaway’s
lawyer, Benny Sharpe, informed the court of the anonymous phone
call received by his office on Saturday, October 10, 1992, which had
advised that Juror Waddell was "a cousin, and may be even a first
cousin of the co-defendant, Kelly Harrington." J.A. 1101f. Sharpe
explained to the court that "[w]e don’t have anything to substantiate
this [information] at this time, and we don’t know where the anony-
mous caller got this information, but we felt we needed to bring this
to the attention" of the court. Id. at 1101f-1101g. Sharpe requested
that the court question Juror Waddell to ascertain his kinship, if any,
to co-defendant Harrington. Id. Sharpe also sought to have the court
examine a transcript of the voir dire proceedings and review Juror
Waddell’s answers to the questions concerning Waddell’s "relation-
ship or knowledge of the incident, or people involved." Id. at 1101g.
The court inquired whether Conaway’s lawyer had found any "author-
ity requiring" a hearing because of an anonymous phone call, and
Sharpe responded that he had not yet checked. Id. The court then
denied all of the defense motions. Id. at 1101h. The court did not
inquire about the apparent nine-day delay in bringing the phone call
to its attention, and no explanation was offered.7

   At the sentencing hearing, Conaway’s lawyers presented the testi-
mony of two witnesses: Cynthia McRae, his cousin, and Dr. Brad
Fisher, a forensic psychologist who had interviewed Conaway and his
family and reviewed his records. Dr. Fisher testified that Conaway
was "disturbed" due to childhood abuse and neglect, and that he had
abused alcohol and drugs since the age of ten. J.A. 1106-09. On cross-
  7
   At trial, Conaway was represented by Sharpe and attorney Kelly Wil-
liams of Rockingham, North Carolina. In his direct appeal, Conaway was
represented by Fred DeVore of Charlotte, North Carolina. In his post-
conviction proceedings in North Carolina, he was represented by Marsh
Smith and Sue Berry of Southern Pines, North Carolina. In these pro-
ceedings, Conaway is represented by Smith, Burton Craige of Raleigh,
North Carolina, and Matthew Stiegler of Durham, North Carolina.
10                          CONAWAY v. POLK
examination, Dr. Fisher opined that Conaway was not mentally
retarded. Id. at 1120-21. He explained that, because Conaway had
scored 79 on an intelligence quotient ("IQ") test in 1977, and scored
80 on a second IQ test in 1982, his IQ scores were above the range
for mental retardation (which is generally defined as an IQ score of
70 or below). Id. For its part, the State presented the jury with the
results of pretrial tests indicating that Conaway’s "intellectual func-
tioning falls within the average range of cognitive abilities." J.A.
1725.

   On the evening of October 19, 1992, at the conclusion of the trial’s
one-day sentencing phase, the jury returned its sentencing verdicts,
recommending that Conaway be sentenced to death on each of the
murder convictions. The trial court accepted the jury’s recommenda-
tions and forthwith imposed two death sentences on Conaway. The
court also sentenced Conaway to forty years in prison on each of the
two kidnapping convictions, forty years for robbery with a dangerous
weapon, and two years on the larceny conviction, to run concurrently
with each other, beginning at the expiration of his death sentences.
State v. Conaway, No. 91 CRS 1721-24 (N.C. Super. Ct. Oct. 19,
1992) (felony judgment).

   Conaway thereafter appealed his convictions and sentences to the
Supreme Court of North Carolina, contending, inter alia, that the
denial of his motions concerning Juror Waddell’s alleged relationship
to co-defendant Harrington had deprived Conaway of his constitu-
tional right to trial before an impartial jury. By its opinion of February
10, 1995, the Supreme Court of North Carolina denied Conaway’s
appellate claims. Conaway, 453 S.E.2d at 831. On the Juror Bias
claim, the court concluded that the trial court had not erred in refusing
to question Juror Waddell, given Conaway’s "critical delay in bring-
ing this alleged telephone call to the trial court’s attention and the lack
of evidence to substantiate this alleged anonymous telephone call." Id.
at 844. The Supreme Court of the United States thereafter denied cer-
tiorari. Conaway v. North Carolina, 516 U.S. 884 (1995).

                                    4.

  On July 22, 1996, Sue Berry and Marsh Smith were appointed as
Conaway’s state post-conviction counsel by the Superior Court of
                            CONAWAY v. POLK                             11
Richmond County. On October 23, 1996, Conaway filed a motion in
Superior Court seeking funds to hire an investigator to assist counsel
on a motion for appropriate relief (an "MAR").8 After the motion for
funds was denied on December 2, 1996, Conaway filed an MAR in
the Superior Court of Richmond County (the "MAR Court") on Janu-
ary 8, 1997, asserting claims not at issue here.

   Meanwhile, Conaway’s lawyers continued their efforts to substan-
tiate the allegation that co-defendant Harrington and Juror Waddell
were related.9 On March 20, 1997, Conaway’s lawyer, Berry, inter-
viewed Harrington in a North Carolina prison. According to affidavits
later filed by Berry, Harrington was "wary and guarded" and "not par-
ticularly knowledgeable of his forebears," but nonetheless confirmed
that he was related to Juror Waddell. J.A. 1553; J.A. 1575. Harrington
provided Berry with his father’s phone number. J.A. 1575. Berry also
sought unsuccessfully to contact Juror Waddell by calling his home
several times in early 1997. On May 13, 1997, Berry called the home
and spoke to a man identifying himself as Juror Waddell’s son, who
informed Berry that Juror Waddell had recently passed away. Id. at
1576. On June 4, 1997, Berry spoke by telephone with co-defendant
Harrington’s father, Theodore Roosevelt "Johnny" Harrington, who
was "curt and somewhat hostile," but nonetheless confirmed that he
was a "double first cousin to Juror Waddell, in that brothers married
sisters." Id. Johnny Harrington also informed Berry that he was aware
that Juror Waddell had passed away. J.A. 1553.
  8
    A defendant convicted of a crime in North Carolina may seek post-
conviction relief by way of an MAR. An MAR is not identical to a
habeas corpus petition, but it provides an avenue to obtain relief from
"errors committed in criminal trials." See N.C. Gen. Stat. § 15A-1401.
  9
    In presenting the facts, we accept the well-pleaded allegations in Con-
away’s petition for habeas corpus relief as being true, and we draw all
reasonable factual inferences in Conaway’s favor. See Walker v. True,
399 F.3d 315, 319 (4th Cir. 2005) (observing that habeas court was
obliged to assess petition using standards for motion to dismiss under
Federal Rule of Civil Procedure 12(b)(6)); Edwards v. City of Goldsboro,
178 F.3d 231, 244 (4th Cir. 1999) (stating that, in addressing Rule
12(b)(6) motion, court must accept all well-pleaded allegations as true,
and draw all reasonable factual inferences in plaintiff’s favor).
12                         CONAWAY v. POLK
   On June 25, 1997, Conaway filed an amended MAR, raising the
Juror Bias claim in the MAR Court for the first time. By that claim,
Conaway contended that he had been denied his right to a "fair and
impartial jury" under both the federal and state constitutions due to
"juror misconduct" on the part of Juror Waddell. J.A. 1440. On Sep-
tember 23, 1997, Conaway requested that the MAR Court conduct an
evidentiary hearing on several issues, including the Juror Bias claim.

   On November 6, 1997, Conaway filed a second amended MAR
("MAR I"), incorporating his previous MARs and particularizing the
Juror Bias claim. In that regard, Conaway contended that his constitu-
tional right to an impartial jury had been contravened because: (1)
Juror Waddell was "presumptively biased" against Conaway due to
Juror Waddell’s "familial relation" to co-defendant Harrington; (2)
Juror Waddell was excusable for cause from the jury; and (3) Juror
Waddell was "untruthful" during the voir dire proceedings. J.A. 1466-
69. Conaway asserted that the "trial jury could not factually accept
Kelly Harrington’s testimony and that of [Conaway]," and that
"[d]isbelieving Kelly Harrington’s testimony would have meant
believing that he was the trigger man or with the trigger man and not
merely present at the scene of a crime." Id. at 1469. MAR I was sup-
ported by an affidavit of attorney Berry, stating that Juror Waddell
was a "double first cousin to the father of Kelly Harrington," and
spelling out the facts surrounding the anonymous phone call received
by the trial lawyer’s office. J.A. 1476.

   On January 22, 1998, the MAR Court denied MAR I on the plead-
ings, without conducting an evidentiary hearing. State v. Conaway,
No. 91 CRS 5877-5878, slip op. at 11 (N.C. Super. Ct. Jan. 22, 1998).
In rejecting the Juror Bias claim, the MAR Court ruled that the
alleged relationship between Juror Waddell and Harrington, if sub-
stantiated, would not contravene either the state or federal constitu-
tion. Id. The MAR Court remarked that Conaway had failed to
support his claim with affidavits or documentary evidence that Har-
rington was, in fact, related to Juror Waddell. Id.10 Conaway peti-
   10
      In denying MAR I, the MAR Court observed that the Juror Bias
claim was procedurally barred "in that [Conaway] could have raised this
on direct appeal and failed to do so." State v. Conaway, No. 91 CRS
5877-5878, slip op. at 11 (N.C. Super. Ct. Jan. 22, 1998). The Juror Bias
claim was, in fact, the first contention addressed and rejected by the
Supreme Court of North Carolina in Conaway’s direct appeal. See State
v. Conaway, 453 S.E.2d 824, 843 (N.C. 1995).
                           CONAWAY v. POLK                            13
tioned the Supreme Court of North Carolina for a writ of certiorari on
the MAR I ruling, but his petition was denied on November 5, 1998.
State v. Conaway, 525 S.E.2d 181 (N.C. 1998).

                                   5.

                                   a.

    On December 31, 1998, Conaway filed a petition for federal habeas
corpus relief in the Middle District of North Carolina asserting, inter
alia, the Juror Bias claim, and requesting an evidentiary hearing in
federal court. By his petition, Conaway alleged: (1) that Juror Wad-
dell was a double first cousin to co-defendant Harrington’s father, see
Pet. ¶ 82; (2) that Juror Waddell did not disclose the familial relation-
ship on voir dire, see id.; (3) that Kelly Harrington was a co-defendant
whose testimony for the State exculpated Harrington by implicating
Conaway, see id. at ¶ 83-84; and (4) that Juror Waddell was subject
to challenge for cause based on his relationship to co-defendant Har-
rington, see id. at ¶ 85-86. In making these allegations, Conaway
incorporated by reference the transcript of the voir dire proceedings
at his trial, as well as the affidavit of Berry, filed in support of MAR
I, stating that Juror Waddell and co-defendant Harrington were double
first cousins, once removed. See id. at ¶ 82.

                                   b.

   On July 9, 1999, Conaway filed a motion in the district court seek-
ing funds to hire an investigator to assist counsel on the Juror Bias
claim. The motion was supported by another affidavit of lawyer
Berry, stating that she had spoken in person with Kelly Harrington
and by telephone with Harrington’s father, each of whom confirmed
their "family relationship" with Juror Waddell. J.A. 1553. On March
8, 2000, the federal magistrate judge declined to authorize the hiring
of an investigator, ruling that Conaway had failed to allege facts that
would entitle him to relief, and that his allegations were speculative.
Conaway v. French, No. 98-1117, slip op. at 2 (M.D.N.C. Mar. 8,
2000).

  On April 4, 2000, Conaway filed a motion for funds to hire a gene-
14                         CONAWAY v. POLK
alogy expert to assist in establishing the familial relationship between
Harrington and Juror Waddell or, alternatively, for authorization, pur-
suant to the applicable rules of procedure, to supplement the record
with affidavits. See 28 U.S.C. foll. § 2254. The motion was supported
by the affidavit of Juror Waddell’s son, Michael Waddell, who stated
that he had lived with Juror Waddell during Conaway’s trial, and that
Juror Waddell knew, prior to serving on the jury, that co-defendant
Harrington was the son of Juror Waddell’s first cousin. J.A. 1564. In
further support of this motion, Conaway submitted the affidavit of his
lawyer Marsh Smith, setting forth, inter alia, his conversations with
Juror Waddell’s daughter, Celia Waddell. By his affidavit, Smith
stated that he had spoken with Ms. Waddell by telephone several
times in 2000. J.A. 1568-69. Smith explained that he had prepared a
draft affidavit for her on the basis of her statements to him, that he
read the draft affidavit to her by phone, and that he revised its con-
tents according to her requests. Id.11 After Ms. Waddell consulted
with her own attorney (to whom Smith referred her), she refused to
execute the affidavit or return Smith’s phone calls. Id. at 1569. Smith
incorporated Ms. Waddell’s draft affidavit into his own affidavit,
specifying therein the evidence that she would present if called to tes-
tify.

   According to Smith’s affidavit, Ms. Waddell would testify to the
following and other facts relevant to the Juror Bias claim:

       • That her "father knew that Kelly Harrington was the son
         of his first cousin, Theodore Roosevelt [Johnny] Har-
         rington, prior to serving on Mr. Conaway’s jury";

       • That the fact that "Kelly Harrington was the son of his
         first cousin is not something my father would have easily
         forgotten";
  11
    Ms. Waddell’s draft affidavit contains handwritten revisions that,
according to Smith, were requested by her attorney. In addition, Smith
filed, as an exhibit to his affidavit, a fax cover sheet dated March 29,
2000, with the subject "Celia Waddell’s Affidavit," from Smith to Ms.
Waddell’s attorney. The fax cover sheet contained a handwritten note
from Smith: "I read this to Celia over the phone last night and she agreed
to sign after she spoke to a lawyer." J.A. 1570.
                           CONAWAY v. POLK                           15
       • That Kelly Harrington bore a "strong resemblance to his
         father [Johnny Harrington]";

       • That she heard Juror Waddell say on several occasions
         prior to Conaway’s trial that "I hope I get on this jury
         because if [Conaway] did it, he should die";

       • That when Juror Waddell was called for jury duty, she
         had a "heated discussion" with him;

       • That she told Juror Waddell "you’re not supposed to be
         on this jury, because you’re related to one of the guys
         involved"; and

       • That she told her father that "not disclosing his family
         relationship to Kelly Harrington was wrong," and he
         responded that she "didn’t know what [she] was talking
         about."

J.A. 1571-72. In testifying, Ms. Waddell would also, according to
Smith, explain the familial relationship between Juror Waddell and
Harrington as follows: Rannie Waddell, Sr. (Juror Waddell’s father)
and Willie Harrington (Kelly Harrington’s grandfather) were half-
brothers who had the same mother. Rannie Waddell, Sr., and Willie
Harrington married sisters, Aggie and Nancy McKay. Their respec-
tive children — including Juror Waddell and Johnny Harrington
(Kelly’s father) — were first cousins who shared three of four grand-
parents (two maternal grandparents and a paternal grandmother). See
id. at 1571.12 By his affidavit, Smith related that he had previously
  12
    Smith explained in his affidavit that Richmond County’s records are
not sufficient to confirm the sibling and cousin relationships described
herein, as the birth indices for African-American children born before
1932 reflect only a child’s last name and the name of one parent. J.A.
1566. Because Johnny Harrington (co-defendant Harrington’s father) and
Juror Waddell were born in 1937, the records were insufficient to estab-
lish that their fathers (respectively Willie Harrington and Rannie Wad-
dell, Sr.) were half-brothers. Id. Smith determined that Johnny
Harrington’s and Juror Waddell’s mothers shared the same last name
(McKay), and their "apparent place" of birth was in the adjacent county
of Marlboro, in South Carolina. Id. at 1566-67.
16                          CONAWAY v. POLK
met with Juror Waddell’s brother, Vance Waddell, who confirmed
that he and Juror Waddell were first cousins to Johnny Harrington,
Kelly’s father. J.A. 1568. According to Smith, Vance Waddell ini-
tially agreed to execute an affidavit to that effect, but he thereafter
failed to return Smith’s calls. Id.13

                                    C.

   On February 8, 2002, the magistrate judge recommended that the
district court deny each of Conaway’s claims for federal habeas cor-
pus relief, including the Juror Bias claim, as well as his request for
funds to hire a genealogy expert and to supplement the record. Con-
away v. French, No. 98-1117, slip op. at 28 (M.D.N.C. filed Feb. 8,
2002). According to the magistrate judge, Conaway had not been dili-
gent in attempting to develop the factual basis for his allegations, in
that he did not attempt to obtain affidavits from Harrington or Wad-
dell’s family until 1997. Id. at 25. The judge further observed that,
even if Conaway’s allegations were true, he had "presented no evi-
dence to show actual bias, and the relationship is not close enough to
presume bias." Id. at 27.14
  13
      Throughout these proceedings, the district court and the State have
treated and accepted the affidavits that Conaway submitted to the district
court as allegations of the petition. We have treated those affidavits in
the same manner for the purposes of this appeal, although, as we explain,
infra note 25, the allegations of the petition are sufficient for purposes
of our rulings on the Juror Bias claim.
   14
      In this appeal, Conaway has been granted leave, pursuant to Local
Rule 28(b), to file attachments to his briefs, including, inter alia: (1) a
2004 email from Celia Waddell (Juror Waddell’s daughter) to Con-
away’s attorney indicating that she would "not sign or give any affidavit
on this matter," that she realized that her decision "could lead to further
legal action granted by[ ] the courts," and that she was "willing to deal
with" such legal action if necessary, see Attachment to Appellant’s Br.
at 2; (2) the 2005 affidavit of Nancy McKay Harrington (co-defendant
Harrington’s grandmother) explaining that the Waddell and Harrington
families were "very close," and that Juror Waddell and Johnny Harring-
ton (co-defendant Harrington’s father) were "first cousins and the same
age" and in the same high school class, so "they spent a lot of time
together," id. at 4; (3) pages from the Rockingham High School year-
                           CONAWAY v. POLK                             17
                                    1.

   In 2001, while Conaway’s habeas corpus petition was pending in
federal court, North Carolina enacted a statute barring the execution
of mentally retarded offenders. See N.C. Gen. Stat. § 15A-2005. A
convicted offender seeking to avoid execution under that statute is
obliged to show that he has "[s]ignificantly subaverage general intel-
lectual functioning, existing concurrently with significant limitations
in adaptive functioning, both of which were manifested before the age
of 18." Id. § 15A-2005(a)(1)(a). The statute defines "[s]ignificantly
subaverage general intellectual functioning" as "[a]n intelligence quo-
tient of 70 or below." Id. § 15A-2005(a)(1)(c).

   Following the enactment of section 15A-2005, Conaway filed
another MAR ("MAR II") in the Superior Court of Richmond County
on January 31, 2002, contending that his death sentence should be
commuted to life in prison because he is mentally retarded under
North Carolina law. In support of MAR II, Conaway submitted the
affidavit of Dr. Fisher stating that: (1) Conaway had scored a 68 on
an IQ test in 2001 (at the age of 34); and (2) Fisher was then (in 2002)
of the opinion that Conaway was mentally retarded, notwithstanding
having testified to the contrary at Conaway’s 1992 sentencing hear-
ing.

  On February 14, 2002, the MAR Court denied MAR II because
Conaway had "presented absolutely no affidavit or documentary evi-

books from 1956 and 1957 showing that Juror Waddell and Johnny Har-
rington were in the same 29-student class section, id. at 15-19; (4)
affidavits from other family members and friends to the same effect; and
(5) the 2005 affidavit of Christopher D. Ricks, the foreman of Con-
away’s jury, stating that a juror closely resembling Juror Waddell was
"particularly adamant about Conaway’s guilt throughout the trial," and
that — prior to deliberations — that juror said "I don’t even know why
we’re doing this . . . that boy is guilty as sin," see Attachment to Reply
Br. at 3. Because these attachments were not submitted to the district
court, we have not considered them in resolving this appeal. We do not,
however, preclude these materials and related evidence from being con-
sidered on remand, to the extent such consideration may be appropriate.
See infra note 28.
18                         CONAWAY v. POLK
dence that [he] had an intelligence quotient of 70 or below before the
age of 18." State v. Conaway, No. 91 CRS 5877-5878, slip op. at 1
(N.C. Super. Ct. Feb. 14, 2002). The court also observed that Dr.
Fisher’s 2002 opinion lacked credibility because he had earlier con-
cluded, in 1992, that Conaway was not mentally retarded, and that an
IQ score of 68 at age 34 did not establish that Conaway had mani-
fested significantly subaverage general intellectual functioning before
the age of 18, as required by section 15A-2005. Id.

   Thereafter, Conaway filed a motion to vacate the denial of MAR
II, which the MAR Court rejected on May 13, 2002. State v. Con-
away, No. 91 CRS 5877-5878 (N.C. Super. Ct. May 13, 2002). Con-
away then petitioned the Supreme Court of North Carolina for a writ
of certiorari on the MAR II ruling. This petition was denied on June
27, 2002. State v. Conaway, 565 S.E.2d 673 (N.C. 2002).

                                   2.

   On June 20, 2002, the Supreme Court of the United States decided
Atkins v. Virginia, holding that the Eighth Amendment to the Consti-
tution precludes the execution of a convicted offender who is men-
tally retarded. See 536 U.S. 304, 321 (2002). In so ruling, the Court
left it to the various states to develop "appropriate ways to enforce the
constitutional restriction" against executing mentally retarded offend-
ers. Id. at 317 (internal quotation marks omitted). On August 22,
2002, Conaway filed an application for habeas corpus in the Supreme
Court of North Carolina, seeking relief, under both North Carolina
law and the Atkins decision, from the MAR Court’s rejection of his
mental retardation claim. On September 3, 2002, Conaway’s state
habeas corpus application was denied. State v. Conaway, 569 S.E.2d
655 (N.C. 2002).

   On October 21, 2002, Conaway sought — and on January 23,
2003, received — leave from the district court to amend his federal
habeas corpus petition to include, inter alia, his claim for relief from
execution under Atkins. In his amended petition, Conaway contended,
inter alia: (1) he is mentally retarded under North Carolina law and
thus entitled to relief from execution under Atkins; and (2) the MAR
Court’s ruling that he was not mentally retarded under North Carolina
                            CONAWAY v. POLK                               19
law deprived him of the due process protections of the Fourteenth
Amendment.

   On July 23, 2003, the federal magistrate judge recommended that
the district court deny the Atkins claim because Conaway had been
accorded an "ample opportunity to litigate the [mental retardation]
issue in state court," and because the MAR Court’s factual determina-
tion was entitled to a presumption of correctness under 28 U.S.C.
§ 2254(e)(1). Conaway v. French, No. 98-1117, slip op. at 11
(M.D.N.C. filed July, 23, 2003). The magistrate judge saw no error
in the MAR Court’s determination that Conaway had failed to estab-
lish that he was mentally retarded under North Carolina law. Id.

                                     D.

   On January 23, 2004, the district court adopted the magistrate
judge’s various recommendations and dismissed Conaway’s petition
for habeas corpus relief in all respects. Conaway v. French, No. 98-
1117 (M.D.N.C. Jan. 23, 2004). Conaway thereafter filed a motion,
pursuant to Federal Rule of Civil Procedure 59(e), to alter or amend
the judgment dismissing his claims. This motion was denied on May
14, 2004.

   On June 10, 2004, Conaway filed a timely notice of appeal. On
April 20, 2005, we granted Conaway the COA on his two appellate
claims: (1) that his Sixth Amendment right to an impartial jury was
contravened because Juror Waddell, on voir dire, concealed his close
familial relationship to co-defendant and key prosecution witness
Harrington (the Juror Bias claim); and (2) that Conaway is entitled to
relief from his death sentences because he is mentally retarded under
North Carolina law (the Atkins claim). We possess jurisdiction pursu-
ant to 28 U.S.C. § 2253.15 As explained below, we remand to the dis-
  15
    Section 2253(a) of Title 28 provides, in relevant part, that "[i]n a
habeas corpus proceeding . . . before a district judge, the final order shall
be subject to review, on appeal, by the court of appeals for the circuit in
which the proceeding is held." Section 2253(c)(1)(A) precludes a court
of appeals from exercising § 2253(a) jurisdiction, "[u]nless a circuit jus-
tice or judge issues a [COA]." Pursuant to § 2253(c)(2), a COA "may
issue . . . . only if the applicant has made a substantial showing of the
denial of a constitutional right."
20                         CONAWAY v. POLK
trict court for an evidentiary hearing on the Juror Bias claim, and we
affirm the court’s dismissal of the Atkins claim.

                                   II.

   We review de novo a district court’s dismissal of a petition for
habeas corpus relief. Conner v. Polk, 407 F.3d 198, 204 (4th Cir.
2005). Pursuant to the Antiterrorism and Effective Death Penalty Act
of 1996 ("AEDPA"), a federal court may only grant habeas corpus
relief on a claim adjudicated "on the merits" by a state court if the
state court’s ruling was either (1) "contrary to, or involved an unrea-
sonable application of, clearly established Federal law, as determined
by the Supreme Court"; or (2) "based on an unreasonable determina-
tion of the facts in light of the evidence presented in the State court
proceedings." 28 U.S.C. § 2254(d). A state court decision constitutes
an "unreasonable" application of federal law if the decision "correctly
identifies the governing legal rule but applies it unreasonably to the
facts of a particular prisoner’s case," Williams (Terry) v. Taylor, 529
U.S. 362, 407-08 (2000), or is "‘unreasonable in refusing to extend
the governing legal principle to a context in which the principle
should have controlled,’" Bates v. Lee, 308 F.3d 411, 417 (4th Cir.
2002) (quoting Ramdass v. Angelone, 530 U.S. 156, 166 (2000) (plu-
rality opinion)). A state court’s findings of fact on a claim being pur-
sued in federal habeas proceedings are presumed correct unless
rebutted by clear and convincing evidence. See 28 U.S.C.
§ 2254(e)(1).

   We review for abuse of discretion a district court’s failure to con-
duct an evidentiary hearing or to authorize discovery proceedings.
Conner, 407 F.3d at 204. In conducting such a review, we are mindful
that, "[b]y definition, a court abuses its discretion when it makes an
error of law." EEOC v. Navy Fed. Credit Union, 424 F.3d 397, 405
(4th Cir. 2005) (internal quotation marks omitted). A petitioner who
has diligently pursued his habeas corpus claim in state court is enti-
tled to an evidentiary hearing in federal court, on facts not previously
developed in the state court proceedings, if the facts alleged would
entitle him to relief, and if he satisfies one of the six factors enumer-
ated by the Supreme Court in Townsend v. Sain, 372 U.S. 293, 313
(1963).16 See Fisher v. Lee, 215 F.3d 438, 454 (4th Cir. 2000). In
  16
    The six Townsend factors, one of which must be satisfied in order to
obtain an evidentiary hearing in a federal habeas corpus proceeding, are:
                            CONAWAY v. POLK                                21
addition, a federal court is not permitted to grant relief to a habeas
corpus petitioner unless the error of which he complains had a "‘sub-
stantial and injurious effect or influence’" on the outcome of the
underlying state court proceeding. Fullwood v. Lee, 290 F.3d 663,
679 (4th Cir. 2002) (quoting Brecht v. Abrahamson, 507 U.S. 619,
637 (1993)).

   In assessing whether a federal habeas corpus petition was properly
dismissed without an evidentiary hearing or discovery, we must eval-
uate the petition under the standards governing motions to dismiss
made pursuant to Rule 12(b)(6) of the Federal Rules of Civil Proce-
dure. See Walker v. True, 399 F.3d 315, 319 n.1 (4th Cir. 2005).
Accordingly, we are obliged to accept a petitioner’s well-pleaded alle-
gations as true, and we are to draw all reasonable inferences there-
from in the petitioner’s favor. See Edwards v. City of Goldsboro, 178
F.3d 231, 244 (4th Cir. 1999).

                                    III.

   By the Juror Bias claim, Conaway contends that Juror Waddell’s
concealment on voir dire of his relationship to co-defendant Harring-
ton, a key prosecution witness, deprived Conaway of his Sixth
Amendment right to trial by an impartial jury. The Sixth Amendment,
made applicable to state criminal proceedings through the Fourteenth,
affords an accused the right to trial by an impartial jury. See Duncan
v. Louisiana, 391 U.S. 145, 160 (1968); Jones v. Cooper, 311 F.3d
306, 310 (4th Cir. 2002). As the Supreme Court has observed, a
"touchstone of a fair trial is an impartial trier of fact — ‘a jury capa-

    (1) the merits of the factual dispute were not resolved in the state
    hearing; (2) the state factual determination is not fairly supported
    by the record as a whole; (3) the fact-finding procedure
    employed by the state court was not adequate to afford a full and
    fair hearing; (4) there is a substantial allegation of newly discov-
    ered evidence; (5) the material facts were not adequately devel-
    oped at the state-court hearing; or (6) for any reason it appears
    that the state trier of fact did not afford the habeas applicant a
    full and fair fact hearing.
Townsend, 372 U.S. at 313 (emphasis added).
22                         CONAWAY v. POLK
ble and willing to decide the case solely on the evidence before it.’"
McDonough Power Equip., Inc. v. Greenwood, 464 U.S. 548, 554
(1984) (quoting Smith v. Phillips, 455 U.S. 209, 217 (1982)).

   In contesting Conaway’s position on the Juror Bias claim, the State
makes three principal contentions: (1) that Conaway procedurally
defaulted on the claim; (2) that the MAR Court’s decision on the
claim was not an unreasonable application of clearly established fed-
eral law as determined by the Supreme Court; and (3) that Conaway
is not entitled to an evidentiary hearing in federal court because he
failed to diligently pursue the Juror Bias claim and because his allega-
tions are insufficient to entitle him to relief thereon. As explained
below, we reject each of these contentions.

                                   A.

   As a preliminary matter, we conclude that Conaway has not proce-
durally defaulted on the Juror Bias claim by failing to support MAR
I with admissible evidence. A claim asserted in a federal habeas cor-
pus proceeding has been procedurally defaulted, and is therefore not
subject to federal review, when "a state court has declined to consider
the claim’s merits on the basis of an adequate and independent state
procedural rule." Fisher v. Angelone, 163 F.3d 835, 844 (4th Cir.
1998). If the decision of the "last state court to which the petitioner
presented his federal claims . . . did not clearly and expressly rely on
an independent and adequate state ground, a federal court may
address the petition." Coleman v. Thompson, 501 U.S. 722, 735
(1991) (recognizing that state court resolution does not "clearly" rest
on independent procedural bar if "interwoven" with federal claim);
see also Jenkins v. Hutchinson, 221 F.3d 679, 682-83 (4th Cir. 2000).

   In asserting that Conaway procedurally defaulted, the State mis-
construes the MAR Court’s decision in MAR I, as well as the govern-
ing procedural requirements in North Carolina. Although the MAR
Court remarked that Conaway had failed to support the claim with
"any affidavit or documentary evidence that Mr. [Waddell] is, in fact,
related to the Co-Defendant Harrington," State v. Conaway, No. 91
CRS 5877-5878, slip op. at 11 (N.C. Super. Ct. Jan. 22, 1998),17 it did
  17
    The MAR Court failed to acknowledge the affidavit of Conaway’s
attorney, Berry, in which she stated that Juror Waddell was a double first
                           CONAWAY v. POLK                             23
not premise its denial of the Juror Bias claim in MAR I on a lack of
admissible evidence (as the State would now have it). Rather, the
MAR Court’s conclusion relied on its determination that the MAR I
allegations, if substantiated, would not "constitute . . . a violation of
the State or Federal Constitution." See id. As the district court recog-
nized, the MAR Court thereby denied the Juror Bias claim "on the
merits." By reaching the merits of the Juror Bias claim, the MAR
Court thus did not "clearly and expressly" rely on an independent and
adequate state procedural rule. See Coleman, 501 U.S. at 735.

   Moreover, contrary to the State’s contention, North Carolina does
not mandate that admissible evidence must be submitted to an MAR
court before an evidentiary hearing can be conducted. See Robinson
v. Polk, ___ F.3d ___, No. 05-01, slip op. at 26 (4th Cir. Feb. 14,
2005). Rather, the applicable North Carolina statute requires that an
MAR premised upon facts not in the trial court record be supported
by "affidavits or documentary evidence." N.C. Gen. Stat. § 15A-
1420(b)(1). There is no authority under North Carolina law (nor has
the State asserted any to us) requiring that such affidavits and docu-
ments themselves constitute admissible evidence. In deciding whether
an evidentiary hearing is warranted, an MAR court is obliged, under
the applicable North Carolina statute, to determine whether the allega-
tions of an MAR and the materials submitted in support thereof raise
questions of fact which, if resolved in the defendant’s favor, would
entitle him to relief. See id. § 15A-1420(c)(1); see also State v.
McHone, 499 S.E.2d 761, 763 (N.C. 1998) ("[A]n evidentiary hearing
is required unless the [MAR] presents assertions of fact which will
entitle the defendant to no relief even if resolved in his favor, or the
[MAR] presents only questions of law."). If such questions are raised,

cousin of co-defendant Harrington’s father. See J.A. 1476. Such an affi-
davit is, in North Carolina, the equivalent to an offer of proof, and it
should have been sufficient to create a question of fact to be resolved in
an evidentiary hearing. See State v. McHone, 499 S.E.2d 761, 764 (N.C.
1998) (remanding for evidentiary hearing where affidavit from prosecu-
tor’s assistant and in-court representation by defense attorney created
question of fact); cf. United States v. Mason, 52 F.3d 1286, 1292 (4th
Cir. 1995) (observing that lawyers are officers of court and subject to
disciplinary action if statements are untrue).
24                         CONAWAY v. POLK
the MAR court must then conduct an evidentiary hearing and, at that
time, assess the admissibility of the proffered evidence. See N.C. Gen.
Stat. § 15A-1420(c)(4). Indeed, it would create a "classic catch-22" if
an MAR defendant were obliged to submit admissible evidence to the
MAR court in order to be accorded an evidentiary hearing, when the
defendant is seeking the hearing because he cannot, without subpoena
power or mechanisms of discovery, otherwise secure such evidence.
See United States v. Mason, 52 F.3d 1286, 1292 (4th Cir. 1995). In
these circumstances, we are unable to conclude that Conaway has
procedurally defaulted on the Juror Bias claim, and he is therefore
entitled to pursue the claim in his federal habeas corpus proceeding.18

                                   B.

  Turning to the merits of the Juror Bias claim, we conclude that the
MAR Court’s denial of MAR I involved an unreasonable application
of clearly established federal law as determined by the Supreme
Court. The text of the Sixth Amendment mandates that "[i]n all crimi-
  18
    On Conaway’s direct appeal, the Supreme Court of North Carolina
explained that the trial court’s failure to question Juror Waddell in
response to Conaway’s motion of October 19, 1992 (before the trial’s
sentencing phase began) was justified in part by Conaway’s "critical
delay" in advising the trial court of the anonymous phone call concerning
Juror Waddell’s relationship to co-defendant Harrington. See State v.
Conaway, 453 S.E.2d 824, 844 (N.C. 1995). And, as Judge Widener
points out in his separate opinion, Conaway and his lawyers could have
brought the phone call to the trial court’s attention earlier. The State,
however, has never asserted that this nine-day delay constituted a proce-
dural default, and we need not, in these circumstances, raise and address
it sua sponte. See Trest v. Cain, 522 U.S. 87, 89 (1997) ("A court of
appeals is not ‘required’ to raise the issue of procedural default sua
sponte."); Yeatts v. Angelone, 166 F.3d 255, 261 (4th Cir. 1999) (observ-
ing that courts should balance comity and efficiency with petitioner’s
"substantial interest in justice" in deciding whether to raise procedural
default sua sponte). In any event, the delay would not constitute a proce-
dural default, as "the last state court" to which Conaway presented the
Juror Bias claim (the MAR Court) "did not clearly and expressly rely on"
— or indeed even reference — the delay. See Coleman, 501 U.S. at 735.
Moreover, Conaway has not asserted here that the delay implicates a
claim of constitutional ineffective assistance by his counsel.
                            CONAWAY v. POLK                              25
nal prosecutions, the accused shall enjoy the right to a . . . trial[ ] by
an impartial jury." U.S. Const. amend. VI. And the Supreme Court
has long recognized that the Sixth Amendment prohibits biased jurors
from serving on criminal juries. See United States v. Wood, 299 U.S.
123, 133 (1936) (recognizing Sixth Amendment’s text prohibits par-
tial jurors, whether bias is "actual or implied"). The Court has
explained that a juror’s bias may be established by showing (1) that
the juror "failed to answer honestly a material question on voir dire";
and (2) that "a correct response [to that question] would have pro-
vided a valid basis for a challenge for cause." See McDonough Power
Equip., Inc. v. Greenwood, 464 U.S. 548, 556 (1984) (the "McDo-
nough test").19 Additionally, a litigant must show that the fairness of
his trial was affected either by the juror’s "motives for concealing
[the] information" or the "reasons that affect [the] juror’s impartial-
ity." Id.20

   By MAR I, Conaway alleged that Juror Waddell failed to disclose
that he was co-defendant Harrington’s double first cousin, once
removed, and Conaway supported his allegations with an affidavit of
his lawyer Berry, as well as the trial’s voir dire transcript. The MAR
Court denied the Juror Bias claim on the merits, concluding that Con-
away’s MAR I allegations, if substantiated, would not "constitute . . .
a violation of the State or Federal Constitution." See State v. Con-
away, No. 91 CRS 5877-5878, slip op. at 11 (N.C. Super. Ct. Jan. 22,
1998). As explained below, the MAR I allegations were sufficient
under McDonough to state a constitutional claim for relief, and thus
the MAR Court’s ruling on the Juror Bias claim was unreasonable.

  19
      Although McDonough was itself a federal civil proceeding, we have
expressly recognized its applicability to Sixth Amendment claims in fed-
eral habeas corpus proceedings instituted by state prisoners. See Jones v.
Cooper, 311 F.3d 306, 310 (4th Cir. 2002).
   20
      The McDonough test for juror bias is generally characterized as hav-
ing two parts. See Jones v. Cooper, 311 F.3d 306, 310 (4th Cir. 2002).
The inquiry into whether a trial’s fairness was affected essentially consti-
tutes a third part, however, as it must be satisfied before the juror’s bias
may be proven. See id. at 313. In any event, we adhere to the uniform
practice of referring to the McDonough test as having two parts.
26                         CONAWAY v. POLK
                                   1.

   Turning to the first part of the McDonough test, Conaway’s allega-
tions in the MAR Court demonstrated that Juror Waddell had "failed
to answer honestly [several] material question[s] on voir dire." See
McDonough, 464 U.S. at 556. On voir dire, Juror Waddell was asked
whether he "kn[e]w any of those people who may testify for the
State." In response, Juror Waddell asserted that he was familiar with
the list of the State’s prospective witnesses, acknowledging only that
he knew Sheriff Jarrell. Juror Waddell was asked whether "a close
friend or family member[ ] had any dealings with the District Attor-
ney’s office," to which he responded negatively. When the prosecutor
asked Juror Waddell whether there was "any reason whatsoever,
whether I’ve asked you or not that you could think of that would keep
you from being fair and impartial in this case," Juror Waddell again
responded, "No."

   Conaway alleged in MAR I that Juror Waddell knew he was
related to co-defendant Harrington, and that Waddell failed to dis-
close this information in response to material questions on voir dire.
Given the multiple questions posed to Juror Waddell that could can-
didly be answered only by acknowledging his kinsman, it was unrea-
sonable for the MAR Court to conclude that Conaway’s MAR I
allegations were insufficient to satisfy the first part of the McDonough
test.

                                   2.

   Conaway’s allegations to the MAR Court also satisfy the second
part of the McDonough test: Had Juror Waddell truthfully responded
at voir dire, his answers "would have provided a valid basis for a
challenge for cause," under the applicable federal constitutional prin-
ciples. See McDonough, 464 U.S. at 556. The Supreme Court has
long recognized the constitutionally based principle that a prospective
juror may be validly challenged for cause if he cannot be impartial.
See, e.g., McDonough, 464 U.S. at 554 ("Voir dire examination serves
to protect th[e] right [to an impartial jury] by exposing possible
biases, both known and unknown, on the part of potential jurors.
Demonstrated bias in the responses to questions on voir dire may
result in a juror’s being excused for cause . . . ."); United States v.
                           CONAWAY v. POLK                            27
Wood, 299 U.S. 123, 133 (1936) ("All persons otherwise qualified for
jury service are subject to examination as to actual bias."). And close
kinship between a juror and a participant in a criminal trial constitutes
a classic form of juror partiality. As far back as the early 1930s, Jus-
tice Cardozo clairvoyantly predicted the factual scenario underlying
the Juror Bias claim when, in writing for the Court, he utilized a
hypothetical juror related to a litigant as the ultimate example of a
partial juror:

    What was sought to be attained was the choice of an impar-
    tial arbiter. What happened was the intrusion of a partisan
    defender. If a kinsman of one of the litigants had gone into
    the jury room disguised as the complaisant juror, the effect
    would have been no different.

Clark v. United States, 289 U.S. 1, 11 (1933) (emphasis added)
(affirming criminal contempt conviction for juror who lied on voir
dire); see also Dyer v. Calderon, 151 F.3d 970, 983 (9th Cir. 1998)
(en banc) ("Just as we would presume bias if the brother of the prose-
cutor were on a jury, we presume bias where a juror lies in order to
secure a seat on the jury.").

   On the basis of Conaway’s allegations in MAR I, Juror Waddell’s
familial relationship to Harrington was sufficiently close that Wad-
dell’s bias would have been "implied" — that is, presumed as a matter
of law. See, e.g., Wood, 299 U.S. at 133 ("The bias of a prospective
juror may be actual or implied; that is, it may be bias in fact or bias
conclusively presumed as [a] matter of law."); see also Jones v. Coo-
per, 311 F.3d 306, 313 (4th Cir. 2002). Such a presumption is justi-
fied where a juror is "a close relative of one of the participants in the
trial or the criminal transaction." See Smith v. Phillips, 455 U.S. 209,
222 (1982) (O’Connor, J., concurring). If Juror Waddell had
responded candidly on voir dire about his relationship to co-defendant
Harrington, the doctrine of implied bias would have provided Con-
away with a valid basis for a challenge for cause."

   In contesting Conaway’s invocation of the implied bias principle,
the State incorrectly asserts that the doctrine of implied bias was abro-
gated by the Court over twenty years ago in Smith v. Phillips. To the
contrary, the doctrine of implied or presumed bias has been recog-
28                         CONAWAY v. POLK
nized from our country’s earliest days, and it remains firmly rooted.
As Judge Kozinski aptly explained in 1998 for an en banc Ninth Cir-
cuit majority:

     Presumed bias dates back in this country at least to Aaron
     Burr’s trial for treason, where Chief Justice Marshall, riding
     circuit, noted that an individual under the influence of per-
     sonal prejudice "is presumed to have a bias on his mind
     which will prevent an impartial decision of the case, accord-
     ing to the testimony." Marshall explained, "He may declare
     that notwithstanding these prejudices he is determined to lis-
     ten to the evidence, and be governed by it; but the law will
     not trust him." United States v. Burr, 25 F. Cas. 49, 50 (D.
     Va. 1807) (emphasis added).

Dyer, 151 F.3d at 984 (presuming bias where juror concealed that her
brother was victim of similar crime). Moreover, as the Dyer court
observed, "[n]o opinion in the two centuries of the Republic . . . has
suggested that a criminal defendant might lawfully be convicted by
a jury tainted by implied bias." Id. at 985; see also Smith, 455 U.S.
at 223 (O’Connor, J., concurring) ("None of our previous cases pre-
clude the use of the conclusive presumption of implied bias in appro-
priate circumstances.").

   To be sure, the Smith Court declined to presume such bias in a set-
ting where a juror had applied for employment with the prosecutor’s
office during the defendant’s trial, and a hearing disclosed no indica-
tion that the juror was, in fact, biased. See 455 U.S. at 212-13. Noth-
ing in the Smith decision, however, indicates that the Court intended
to discard the doctrine of implied or presumed bias. Indeed, Justice
O’Connor wrote separately on this point, expressing her "view that
the [majority] opinion does not foreclose the use of ‘implied bias’ in
appropriate circumstances," such as a close familial relationship. Id.
at 221-22 (O’Connor, J., concurring). And in McDonough, decided by
the Court two years after Smith, five Justices wrote or joined concur-
ring opinions emphasizing that the doctrine of implied bias was yet
available. See McDonough, 464 U.S. at 556-57 (Blackmun, J., con-
curring, joined by Stevens, J., and O’Connor, J.) (observing that "in
exceptional circumstances,[ ] the facts are such that bias is to be
inferred"); id. at 558 (Brennan, J., concurring in the judgment, joined
                            CONAWAY v. POLK                              29
by Marshall, J.) (recognizing that "[b]ecause the bias of a juror will
rarely be admitted by the juror himself . . . it necessarily must be
inferred from surrounding facts and circumstances"); see also Solis v.
Cockrell, 342 F.3d 392, 395 n.6 (5th Cir. 2003) (noting that five Jus-
tices in McDonough agreed on "vitality" of implied bias doctrine).21
It would be unreasonable to conclude, as the State urges here, that this
bedrock principle of constitutional jurisprudence was abandoned
without so much as a whisper from the Supreme Court.

  Not surprisingly, each court of appeals to have addressed the issue
agrees that the doctrine of implied bias remains, after Smith, a settled
constitutional principle.22 As the Fifth Circuit observed, "[w]hile the
  21
      We have consistently treated Justice O’Connor’s concurrence in
Smith as the authoritative articulation of implied bias. See, e.g., Person
v. Miller, 854 F.2d 656, 664 (4th Cir. 1988) (recognizing implied bias
principle as limited to extreme situations where relationship between
prospective juror and litigation such that "it is highly unlikely that the
average person could remain impartial in his deliberations under the cir-
cumstances" (citing Smith, 455 U.S. at 222 (O’Connor, J., concurring))).
   22
      Since the Court’s 1982 decision in Smith, at least ten circuits have
recognized the continuing viability of the implied bias principle. See
United States v. Scott, 854 F.2d 697, 699 (5th Cir. 1988) (presuming bias
where juror failed to disclose that his brother worked in sheriff’s office);
Hunley v. Godinez, 975 F.2d 316, 320 (7th Cir. 1992) (affirming finding
of implied bias where jury was burglarized while sequestered during trial
concerning similar burglary); Green v. White, 232 F.3d 671, 678 (9th Cir.
2000) (recognizing "implied bias" where juror lied about felony convic-
tions); Burton v. Johnson, 948 F.2d 1150, 1158 (10th Cir. 1991) (affirm-
ing finding of implied bias where juror was abused in similar manner as
victim); Isaacs v. Kemp, 778 F.2d 1482, 1489 (11th Cir. 1985) (presum-
ing bias due to pervasive pretrial publicity); see also Amirault v. Fair,
968 F.2d 1404, 1405-06 (1st Cir. 1992) (recognizing implied bias doc-
trine but declining to award relief under circumstances); United States v.
Torres, 128 F.3d 38, 45-46 (2d Cir. 1997) (same); United States v. Cala-
brese, 942 F.2d 218, 224 (3d Cir. 1991) (same); Zerka v. Green, 49 F.3d
1181, 1186 n.7 (6th Cir. 1995) (same); Cannon v. Lockhart, 850 F.2d
437, 440-41 (8th Cir. 1988) (same). To be sure, we suggested in Conner
v. Polk that there might be "some question" after Smith whether implied
bias remained a viable doctrine. See 407 F.3d 198, 206 n.4 (4th Cir.
2005). As our analysis here demonstrates, however, it could not reason-
ably be concluded that Smith overturned two centuries of Supreme Court
precedent by declining to presume bias in a particular set of circum-
stances.
30                          CONAWAY v. POLK
Supreme Court has oft-rejected application of the implied bias princi-
ple, . . . it has never rejected the principle itself." Brooks v. Dretke,
418 F.3d 430, 435 (5th Cir. 2005) (reversing death sentence due to
presumption of bias where juror was charged during trial with weap-
ons offense by district attorney’s office which was prosecuting case).
In these circumstances, we are constrained to agree with the observa-
tion of Judge Kozinski in Dyer: "Courts disagree (e.g., Smith) about
when the doctrine applies, not whether it exists." Dyer, 151 F.3d at
985 n.24. Accordingly, the implied bias principle constitutes clearly
established federal law as determined by the Supreme Court. And, on
the basis of Conaway’s MAR I allegations, it was unreasonable for
the MAR Court to conclude that, even if Juror Waddell had been can-
did on voir dire, Conaway would nevertheless have lacked a valid
basis for challenging Juror Waddell for cause.23

                                     3.

   Even where, as here, the two parts of the McDonough test have
been satisfied, a juror’s bias is only established under McDonough if
the juror’s "motives for concealing information" or the "reasons that
affect [the] juror’s impartiality can truly be said to affect the fairness
of [the] trial." McDonough, 464 U.S. at 556; see also Conner v. Polk,
407 F.3d 198, 206-07 (4th Cir. 2005). In MAR I, Conaway alleged
facts sufficient to establish that Juror Waddell concealed crucial infor-
mation in order to serve on Conaway’s jury. Such "dishonesty, of
itself, is evidence of bias." Burton v. Johnson, 948 F.2d 1150, 1159
(10th Cir. 1991); see also United States v. Colombo, 869 F.2d 149,
151-52 (2d Cir. 1989) (recognizing that lying during voir dire is
  23
    Although unnecessary to our resolution of the Juror Bias claim, we
note that applicable state jury selection principles would also have pro-
vided a valid basis for challenging Juror Waddell for cause. See N.C.
Gen. Stat. § 15A-1212(5) (providing that prospective juror may be chal-
lenged for cause if "related by blood or marriage within the sixth degree
to the defendant or the victim of the crime"); see also State v. Allred, 169
S.E.2d 833 (N.C. 1969). In this proceeding, the State concedes that,
under Conaway’s allegations, Juror Waddell and co-defendant Harring-
ton are related by blood within the fifth degree under North Carolina law.
See Appellee’s Br. at 34; see also N.C. Gen. Stat. § 104A-1(2) (defining
degrees of kinship).
                           CONAWAY v. POLK                           31
inconsistent with obligation to "weigh the evidence fairly and obey
the instructions of the court").

   Moreover, Juror Waddell’s relationship to co-defendant Harrington
necessarily affected the fairness of Conaway’s trial. Put simply, Con-
away’s trial was a swearing match, with Conaway and his co-
defendants accusing each other of the heinous murders of Weather-
ford and Callahan. As the prosecutor acknowledged in his closing
argument, the jury could not convict Conaway without crediting Har-
rington’s version of events over that presented in Conaway’s own tes-
timony. See J.A. 1082 ("[I]f you believe what Kelly Harrington told
you . . . [y]ou can convict Mr. Conaway of all the charges. If you
believe Mr. Conaway . . . then you will acquit Mr. Conaway. It’s
really simple."). And as Lord Coke aptly observed, "no matter how
remote soever, . . . the law presumeth that one kinsman doth favor
another before a stranger." State v. Allred, 169 S.E.2d 833, 837 (N.C.
1969) (quoting Thomas’s Coke, 3 Vol. 518) (internal quotation marks
omitted).

   As a result, it was unreasonable for the MAR Court to conclude
that the allegations in MAR I were legally insufficient, under the
clearly established McDonough principles, to show that juror bias
infringed Conaway’s constitutional right to an impartial jury. Sec-
tion 2254(d)(1) of AEDPA therefore does not preclude Conaway
from obtaining federal habeas corpus relief on the Juror Bias claim,
because the MAR Court’s decision involved an unreasonable applica-
tion of clearly established federal law as determined by the Supreme
Court.

                                  C.

   For similar reasons, the district court erred in dismissing the Juror
Bias claim without an evidentiary hearing. As explained below, the
district court erroneously determined that 28 U.S.C. § 2254(e)(2) pre-
cluded Conaway from being accorded an evidentiary hearing on that
claim, and it erred in ruling that Conaway had not alleged facts suffi-
cient to entitle him to relief.

  Under AEDPA, a federal district court may not ordinarily grant an
evidentiary hearing on a claim that was presented to a state court
32                          CONAWAY v. POLK
when the petitioner "has failed to develop the factual basis of a claim
in State court proceedings." See § 2254(e)(2). A petitioner has not
"failed to develop" the facts of his claim, however, if he has "made
a reasonable attempt, in light of the information available at the time,
to investigate and pursue claims in state court." Williams (Michael)
v. Taylor, 529 U.S. 420, 435 (2000). At a minimum, a diligent peti-
tioner must "seek an evidentiary hearing in state court in the manner
prescribed by state law." Id. at 437.

   On the facts presented in this record, Conaway reasonably
attempted, in light of the information available to him at the relevant
times, to investigate and pursue the Juror Bias claim in state court.
His efforts were thwarted, however, by reluctant witnesses and
unreceptive courts. Conaway’s direct appeal was not resolved until
October 1995, and his post-conviction lawyers were not appointed
until July 1996. Although Conaway’s request for funds to hire an
investigator was denied, his attorneys personally investigated the
Juror Bias claim, sometimes at their own expense. See, e.g., J.A.
1575. Despite their efforts, potential witnesses in both the Waddell
and Harrington families were reluctant to cooperate with the lawyers,
or they flatly refused to do so. And, as Conaway’s lawyer Smith
explained by affidavit, the official records of Richmond County are
insufficient — apparently for race-based reasons — to establish the
relationship between Juror Waddell and co-defendant Harrington.
Moreover, Conaway’s request for an evidentiary hearing in the MAR
Court was denied, depriving him of the opportunity to build a factual
record. Because Conaway has been reasonably diligent in pursuing
his claim, and his failure to fully develop the facts related to the Juror
Bias claim in state court is attributable to external causes,
§ 2254(e)(2) does not preclude him from being accorded an evidenti-
ary hearing in federal court. See Williams, 529 U.S. at 443.

   When a state court has denied a habeas corpus petitioner the oppor-
tunity to develop his claims, he is entitled to an evidentiary hearing
in federal court if he can establish one of the six factors enumerated
by the Supreme Court in Townsend v. Sain, 372 U.S. 293 (1963), and
if he has alleged facts which, if true, would entitle him to relief. See
Walker v. True, 399 F.3d 315, 327 (4th Cir. 2005). A petitioner is not
to be awarded relief, however, on the basis of an error that was harm-
less, in that it did not have a "‘substantial and injurious effect or influ-
                            CONAWAY v. POLK                              33
ence’" on the outcome of the underlying proceeding. Fullwood v. Lee,
290 F.3d 663, 679 (4th Cir. 2002) (quoting Brecht v. Abrahamson,
507 U.S. 619, 637 (1993)). And where the court is in "grave doubt,"
as to the effect of a constitutional error — that is, if the court is in
"virtual equipoise" regarding an error’s harmlessness — the petitioner
is entitled to an evidentiary hearing. See Fullwood, 290 F.3d at 679.

   Conaway has never been afforded an opportunity to develop the
facts underlying the Juror Bias claim, and he can therefore satisfy at
least the fifth Townsend factor. See Townsend, 372 U.S. at 313 (list-
ing factors that require hearing, including "(5) the material facts were
not adequately developed at the state-court hearing"). And, as our
foregoing analysis demonstrates, Conaway has stated a valid claim for
relief under McDonough: Conaway has alleged in his federal habeas
corpus petition, as he did in MAR I, that Juror Waddell concealed his
relationship to co-defendant Harrington during the voir dire proceed-
ings, which affected the fairness of Conaway’s trial.

   Furthermore, in addition to the MAR I allegations, Conaway has
alleged in his federal proceedings that, during voir dire, Juror Waddell
failed to honestly answer several material questions — such as
whether he had formed any opinion concerning Conaway’s trial —
that would have exposed Juror Waddell’s previous statements that he
"hope[d to] get on this jury because if [Conaway] did it, he should die."24
In Morgan v. Illinois, the Supreme Court reiterated that "[a] juror who
will automatically vote for the death penalty in every case will fail in
good faith to consider the evidence of aggravating and mitigating cir-
  24
    Although Conaway did not seek relief in MAR I based on Juror
Waddell’s statements that Conaway should die, he cannot be faulted for
his failure to do so. Conaway had not yet discovered Juror Waddell’s
statements because, under these allegations, Waddell had concealed
them, and Conaway’s efforts to obtain information from Juror Waddell’s
family — without the mechanisms of discovery — had yet proved fruit-
less. See Williams, 529 U.S. at 442-43 ("The Virginia Supreme Court’s
denial of the motion [concerning juror bias] is understandable in light of
petitioner’s vague allegations, but the vagueness was not the fault of peti-
tioner. . . . The underdevelopment of these matters was attributable to
[the juror and the prosecutor who failed to disclose their past profes-
sional relationship], if anyone.").
34                          CONAWAY v. POLK
cumstances as the instructions require him to do." See 504 U.S. 719,
729 (1992). Accordingly, Juror Waddell could have been challenged
for cause under Morgan if he had answered truthfully on voir dire.
And as the Court said, if "even one such juror is empaneled and the
death sentence is imposed, the State is disentitled to execute the sen-
tence." Id.

   Conaway has alleged that he was convicted and sentenced to death
by a jury that included a primary accuser’s double first cousin, once
removed, and his affidavits reflect that the juror had previously
asserted that, if Conaway was guilty, he should die. In these circum-
stances, we need not labor to conclude that such a serious constitu-
tional injury affected Conaway’s substantial rights, nor are we in
doubt as to the necessity of an evidentiary hearing. See Fullwood, 290
F.3d at 682 (concluding that allegations that spouse pressured juror
to vote for death sentence "are of a type that draw into question the
integrity of the verdict, and give rise to a presumption of prejudice"
(internal quotation marks and citation omitted)). Yet Conaway has
never been accorded the opportunity to develop the facts underlying
his claim. See Townsend, 372 U.S. at 313. As the Supreme Court has
"long held," the "remedy for allegations of juror partiality is a hearing
in which the defendant has the opportunity to prove actual bias." See,
e.g., Smith v. Phillips, 455 U.S. 209, 215 (1982). The district court
therefore committed an error of law — and abused its discretion —
in denying Conaway an evidentiary hearing on the Juror Bias claim.25

                                    IV.

   Finally, we turn to the Atkins claim, which was first raised in MAR
II, and upon which we also awarded the COA. On appeal, Conaway
asserts that the district court erred in denying him an evidentiary hear-
ing to prove that he is entitled to relief from execution under Atkins
  25
    Consistent with the manner in which the State and the district court
treated the materials filed in the district court, we have considered affida-
vits submitted by Conaway to the district court that were not initially
incorporated into his petition for habeas corpus. See supra note 13. As
demonstrated by our analysis in Part III.B, however, the allegations of
the petition alone, assessed under Rule 12(b)(6) principles, are sufficient
to entitle Conaway to relief on the Juror Bias claim.
                           CONAWAY v. POLK                            35
v. Virginia, 536 U.S. 304 (2002). In Atkins, the Court declared that
the execution of mentally retarded offenders contravenes the Eighth
Amendment’s prohibition against cruel and unusual punishment. Id.
at 321. In so doing, the Court left to the various states "the task of
developing appropriate ways to enforce the constitutional restriction."
Id. at 317 (internal quotation marks omitted). Accordingly, to prevail
on the Atkins claim, Conaway must show that he should be deemed
mentally retarded under North Carolina law. See Walker v. True, 399
F.3d 315, 319 (4th Cir. 2005).

   In North Carolina, a convicted offender seeking to prove that he is
mentally retarded is obliged to prove that he has (1) "significantly
subaverage general intellectual functioning," and (2) "significant limi-
tations in adaptive functioning," both of which had "manifested
before the age of 18." N.C. Gen. Stat. § 15A-2005(a)(1)(a) & (a)(2).
The statute defines "significantly subaverage general intellectual
functioning" as "[a]n intelligence quotient of 70 or below." Id. § 15A-
2005(a)(1)(c).26

   Conaway contends in these proceedings, as he did in MAR II, that
he is entitled to be deemed mentally retarded because he has an IQ
of 68 and a lifetime record of major impairment in academics,
employment, and life skills. In support of MAR II, Conaway submit-
ted the affidavit of Dr. Fisher, asserting that Conaway had scored 68
on an IQ test in 2001 (when Conaway was 34 years old), and that,
based on a 2001 examination, Fisher believed Conaway to be men-
tally retarded. The MAR Court rejected Conaway’s claim, concluding
that Conaway had consistently received an IQ score of 79 or 80 on
tests administered prior to the age of 18, and had "presented abso-
lutely no affidavit or documentary evidence that [he] had an [IQ] of
70 or below before the age of 18." State v. Conaway, No. 91 CRS
5877-5878, slip op. at 1 (N.C. Super. Ct. Feb. 14, 2002). The MAR
Court further explained that the IQ score of 68 represented only Con-
  26
    In order to show "significant limitations in adaptive functioning," a
North Carolina offender must show limitations in at least two adaptive
skill areas, including: "communication, self-care, home living, social
skills, community use, self-direction, health and safety, functional aca-
demics, leisure skills, and work skills." N.C. Gen. Stat. § 15A-
2005(a)(1)(b).
36                          CONAWAY v. POLK
away’s "current" score — that is, it did not show that Conaway had
manifested the requisite IQ of 70 or below before the age of 18 —
and that Fisher had testified at Conaway’s 1992 sentencing hearing
that Conaway was not mentally retarded. Id.

   Although the MAR Court denied MAR II prior to the Supreme
Court’s Atkins decision, it determined that Conaway is not mentally
retarded under North Carolina law, thereby deciding the dispositive
issue in the Atkins claim. Accordingly, the court’s disposition of
MAR II constitutes an adjudication "on the merits" of the Atkins
claim for purposes of AEDPA. See Early v. Packer, 537 U.S. 3, 7-8
(2002) (per curiam) (concluding that state court ruling which did not
cite Supreme Court precedent was nonetheless "on the merits"); Hill
v. Ozmint, 339 F.3d 187, 196 (4th Cir. 2003) ("[A] state court may
adjudicate a claim ‘on the merits’ without relying on or citing relevant
Supreme Court precedents." (citing Early)). On the record before the
MAR Court, neither its application of the law nor its determination
of the facts on the Atkins claim was unreasonable. See 28 U.S.C.
§ 2254(d)(1)-(2). We therefore affirm the district court’s denial of the
Atkins claim.27

                                    V.

   Pursuant to the foregoing, we affirm the district court’s dismissal
of the Atkins claim. On the other hand, we remand for an evidentiary
hearing on the Juror Bias claim and for such other and further pro-
ceedings as may be appropriate.28
  27
      Significantly, Conaway has never alleged facts to support the conclu-
sion that any of his childhood IQ tests could be unreliable as to whether
his IQ was above 70 at the time the test was administered. Cf. Walker,
399 F.3d at 321-22 (discussing how IQ score of 76 could show IQ of 70,
when accounting for "Flynn effect" and "standard error of measure-
ment").
   28
      We have not, in disposing of this appeal, taken into account the
attachments submitted by Conaway to his briefs on appeal. See supra
note 14. The district court may, however, to the extent it deems them rel-
evant and admissible, consider such attachments and related materials on
remand.
                          CONAWAY v. POLK                             37
                                              AFFIRMED IN PART
                                         AND REMANDED IN PART

WIDENER, Circuit Judge, concurring:

   I concur in the majority opinion in the decision that Conaway’s
execution is not precluded by the Eighth Amendment under Atkins v.
Virginia, 536 U.S. 304 (2002). I also concur in the remand of the case
for further consideration of the juror bias claim, but for a different
reason than does the majority.

   Conaway’s attorneys knew of the telephone call with respect to the
relationship between the juror Waddell and the witness and co-
defendant Harrington at 1:45 p.m. October 10, 1992. October 10 was
two days prior to the commencement of the trial, which started on
October 12, 1992 with the empaneling of the jury, it having not been
previously sworn, although selected, in proceedings in the trial court
from Monday, October 5 through Friday, October 9, 1992. The tele-
phone call referred to was described as anonymous and as follows:

    The gist of the call was that juror No. 1, I believe, is a cou-
    sin, and may be even a first cousin of the co-defendant Kelly
    Harrington. J.A. 1101f.

   The jury had not been empaneled until the trial began, the morning
of October 12, and North Carolina law was quite clear that the juror
Waddell was disqualified as a cousin of a prosecuting witness as a
matter of law under State v. Allred, 169 S.E. 2d 833 (N.C. 1969). But
no challenge was made to the seating of Waddell at that time, or later,
before verdict, and Conaway’s attorneys moved only that the trial
court "examine, juror No. 1, [Waddell] to ascertain his kinship, if
any." The motion was denied. J.A. 1101g.

   The trial on the merits commenced on October 12th, and continued
on October 13, 14 and 15, when the case was sent to the jury. The
jury returned its verdict the afternoon of the 15th. Conaway testified
for himself on October 14th and 15th, and Harrington had testified on
October 12th and 13th on behalf of the State. Both were cross-
examined, as were all of the witnesses whose testimony was other
38                         CONAWAY v. POLK
than purely routine and subject to little contradiction or interpretation.
Through all four days of the trial on the merits, Conaway and his
attorneys sat silent as to Waddell’s disqualification, with the disquali-
fied juror, Waddell, sitting on the jury. This was no helter-skelter
defense but was active and strenuous. I am convinced that, on this
record, Conaway and his attorneys suffered Waddell to be on the jury
and cannot now take advantage of any error relating to his sitting.
