                       PUBLISHED


UNITED STATES COURT OF APPEALS
             FOR THE FOURTH CIRCUIT


UNITED STATES OF AMERICA,             
                Plaintiff-Appellee,
               v.                          No. 11-4052
TIMOTHY TYRONE HORTON,
             Defendant-Appellant.
                                      
        Appeal from the United States District Court
 for the Eastern District of North Carolina, at Wilmington.
            James C. Fox, Senior District Judge.
                    (5:08-cr-00060-F-1)

                  Argued: May 18, 2012

                 Decided: August 30, 2012

  Before AGEE, DAVIS, and THACKER, Circuit Judges.



Affirmed in part, vacated in part, and remanded in part by
published opinion. Judge Agee wrote the opinion, in which
Judge Thacker joined. Judge Davis wrote a separate opinion
concurring in part and concurring in the judgment


                        COUNSEL

ARGUED: Samuel A. Forehand, LAW OFFICE OF SAM-
UEL A. FOREHAND, PA, Raleigh, North Carolina, for
Appellant. Kristine L. Fritz, OFFICE OF THE UNITED
2                    UNITED STATES v. HORTON
STATES ATTORNEY, Raleigh, North Carolina, for Appel-
lee. ON BRIEF: Thomas G. Walker, United States Attorney,
Jennifer P. May-Parker, Assistant United States Attorney,
OFFICE OF THE UNITED STATES ATTORNEY, Raleigh,
North Carolina, for Appellee.


                             OPINION

AGEE, Circuit Judge:

   Timothy Tyrone Horton appeals his conviction for possess-
ing a firearm while a convicted felon, in violation of 18
U.S.C. §§ 922(g)(1) and 924, and also appeals the district
court’s imposition of a sentence of life imprisonment. For the
reasons set forth herein, we affirm Horton’s conviction. We
conclude, however, that the district court erred in applying the
murder cross-reference provision in United States Sentencing
Guidelines Manual ("USSG" or "Guidelines") § 2K2.1(c)(1)
and in treating as relevant conduct a murder that occurred dur-
ing the course of an unrelated and uncharged offense, which
error substantially increased Horton’s advisory Guidelines
range. Accordingly, we vacate Horton’s sentence and remand
for resentencing.

            I.   Background and Proceedings Below

   The offense for which Horton was charged, and ultimately
convicted by a jury, occurred on August 10, 2007.1 On that
date, Horton was at the home of his girlfriend, Timeca Bryant.
The couple argued after Ms. Bryant learned Horton had a gun,
which he told her he was holding for a friend. Horton left the
home and, while outside, fired three shots, one of which hit
Ms. Bryant’s unoccupied vehicle. He fired the other two into
the air. Ms. Bryant came out and obtained Horton’s gun. She
    1
   We provide a broad overview of the facts here and discuss additional
procedural and factual aspects of the case in context.
                    UNITED STATES v. HORTON                   3
then returned to her home, taking the gun with her, and locked
herself inside. Once inside, she called the police, and Horton
left the premises. When police arrived, officers found three
spent .22 casings, a bullet hole in Ms. Bryant’s car, and
retrieved from Ms. Bryant the gun—a .22 rifle with a sawed-
off stock and sawed-off barrel. Investigation revealed that the
gun had been stolen during a breaking and entering of an
Exxon store in July 2006.

  In February 2008, Horton contacted the police and said he
wanted to speak with them about this incident, at which point
he confessed to possession of the gun on August 10, 2007. He
was arrested and charged in this case with violating 18 U.S.C.
§§ 922(g)(1) and 924, being a felon in possession of a fire-
arm.

   Horton pled not guilty and proceeded to a trial by jury. The
jury in his first trial was unable to reach a verdict and the
court declared a mistrial. After a second trial, the jury found
Horton guilty and he was sentenced by the district court to life
imprisonment. Horton filed a timely motion for new trial,
which the district court denied. He timely appealed from both
the conviction and sentence, and from the denial of his motion
for new trial.

  This Court has jurisdiction pursuant to 28 U.S.C. § 1291
and 18 U.S.C. § 3742.

              II.   Challenges to the Conviction

   Horton raises two challenges to his conviction. First, he
contends that the district court abused its discretion in deny-
ing his motion for substitution of counsel. Second, he argues
that the district court abused its discretion in denying his
motion for new trial predicated on what Horton describes as
the Government’s failure to disclose material impeachment
evidence under Brady v. Maryland, 373 U.S. 83 (1963). For
4                   UNITED STATES v. HORTON
the reasons discussed below, we reject both of these chal-
lenges.

              A.   Motion to Substitute Counsel

   We first address Horton’s claim that the district court erred
in denying his motion for substitute counsel. Clarke Speaks
was appointed as Horton’s counsel on March 25, 2008. On
October 1, 2008, two months before his scheduled arraign-
ment, Horton filed a pro se motion for substitute counsel, his
first such motion. In the motion, Horton asserted that he was
"not satisfied with Mr. Clark Speaks [sic] representation and
believe[d] it [to] be in [his] best [i]nterest for a change of
counsel . . . ." (JA 87.) He offered no additional details in sup-
port of his motion.

   The district court denied the motion without a hearing in an
order filed October 7, 2008. In that order, the court "advised"
Horton that, although "he has a Constitutional right to court-
appointed counsel if he is unable to afford an attorney, he is
not entitled to appointment of the attorney of his choice." (JA
88 (citations omitted).) The order further informed Horton
that he could "go forward with his court-appointed counsel,
Mr. Speaks," or he could "represent himself, with Mr. Speaks
acting as back-up counsel to assist him with legal questions
that may arise." (Id. at 89.) In its order, the district court also
noted that Horton would be required prior to his arraignment
on December 8, 2008, to advise the court under oath whether
he wanted to continue with Speaks’ representation or to repre-
sent himself with Speaks as back-up counsel. This inquiry
never took place, although the court did ask general questions
regarding Horton’s satisfaction with this attorney, and Horton
did not express any dissatisfaction. Neither Horton nor Speaks
ever raised the issue with the court again and Speaks repre-
sented Horton at both trials.

   On February 17, 2010, approximately three months after
the jury verdict convicting Horton, Speaks moved to with-
                   UNITED STATES v. HORTON                    5
draw from representation. His motion included the statement
that he and Horton, "[d]uring the course of the Attorney-
Client Relationship . . . have reached an impasse resulting
from irreconcilable differences" and that this impasse was
"prevent[ing] the communication necessary to prepare and
implement an adequate defense." (JA 587.) The court granted
the motion without a hearing, and directed the Federal Public
Defender to assign substitute counsel, which was done.

   We review the denial of Horton’s motion for substitute
counsel for abuse of discretion. See United States v. Smith,
640 F.3d 580, 587-91 & n.6 (4th Cir. 2011). In cases where
a district court has denied a request by a defendant to replace
one court-appointed lawyer with another court-appointed law-
yer, this Court considers three factors to determine whether
the initial appointment "ceased to constitute Sixth Amend-
ment assistance of counsel": "(1) the timeliness of the motion;
(2) the adequacy of the court’s subsequent inquiry; and (3)
‘whether the attorney/client conflict was so great that it had
resulted in total lack of communication preventing an ade-
quate defense.’" Id. at 588 (quoting United States v. Gallop,
838 F.2d 105, 108 (4th Cir. 1988)).

   Applying these factors here, it is clear that the motion was
timely made, and the Government does not contend other-
wise. Similarly, the Government does not contend-nor could
it-that the district court made any inquiry into the reasons for
Horton’s dissatisfaction with his counsel. This fact distin-
guishes this case from Smith, in which there was at least some
inquiry into the reasons for the dissatisfaction and we held
there was no abuse of discretion. Here, because of the district
court’s complete failure to conduct any inquiry, this Court is
essentially left with an incomplete record upon which to
determine the third factor: the extent of the breakdown in
communication and whether it was so great that it prevented
an adequate defense. Accordingly, we will assume, without
deciding, that the district court abused its discretion in deny-
ing Horton’s motion without conducting any inquiry into the
6                  UNITED STATES v. HORTON
reasons for his dissatisfaction with counsel or any inquiry as
to the extent of any breakdown in communication.

   We nonetheless conclude that Horton is not entitled to a
reversal of his conviction because the error was harmless and
did not result in any prejudice to him. See, e.g., Fed. R. Crim.
P. 52(a) ("Any error, defect, irregularity, or variance that does
not affect substantial rights must be disregarded."); United
States v. Young, 470 U.S. 1, 13 n.10 (1985) (in addressing
claim of prosecutorial misstatements, "a reviewing court
could reverse an otherwise proper conviction only after con-
cluding that the error was not harmless."); United States v.
Wilks, 46 F.3d 640, 644 (7th Cir. 1995) ("Even if . . . the dis-
trict court abused its discretion when it denied [the defen-
dant’s] request for new counsel, such an error [was] harmless"
because defendant failed to show that counsel rendered con-
stitutionally ineffective assistance and thus there was no Sixth
Amendment violation).

  In this case, there is clear evidence that Speaks provided an
adequate defense at both trials. For example, he filed pre-trial
motions in limine, he cross-examined government witnesses,
and he strongly advocated for his client throughout both trial
proceedings. Indeed, the first trial resulted in a hung jury,
which is attributable in some part to Speaks’ performance as
an adequate advocate for Horton.

   Notably, Horton does not identify—let alone show—any
specific way in which his defense was hampered by any lack
of communication with his counsel. In fact, on two different
occasions after Horton’s motion to substitute was denied, he
appeared before the district court and was placed under oath.
By his failure to assert otherwise in response to questions
posed by the court, Horton indicated that he had "ample
opportunity to discuss his case with his attorney," that he had
"discussed his case with his attorney," and that he was "com-
pletely and fully satisfied with his attorney’s services." (JA
103, JA 120.) Thus, Horton’s own representations to the court
                      UNITED STATES v. HORTON                           7
refute that there were significant communication problems
prior to or during the trials.2

   The record indicates that at some point after Horton was
convicted and prior to sentencing, when counsel asked to
withdraw and was in fact replaced, communication had bro-
ken down to some extent between Speaks and Horton. But
based on the complete record before us, we conclude that any
error in failing to appoint substitute counsel at the time Hor-
ton requested it was harmless. Accordingly, Horton is not
entitled to have his conviction vacated on this ground.

                    B.    Motion for New Trial

   Horton’s second challenge to his conviction is based on the
district court’s denial of his motion for a new trial. In that
motion, he alleged that the Government failed to disclose
material impeachment evidence until after his trials. He
argues on appeal that the district court’s order denying his
motion constituted an abuse of discretion and that he is enti-
tled to a new trial.

   Horton’s argument as to the alleged Brady evidence
focuses on the testimony of two police officers regarding his
confession to the charged offense, which was not videotaped,
and the reasons for the failure to do so. Specifically, at both
trials the juries heard evidence concerning Horton’s unre-
corded confession to possessing the firearm, which he made
  2
   While these representations to the court further support our conclusion
that Horton and his counsel were still able to communicate and that Hor-
ton’s Sixth Amendment right to counsel was not violated, we do not treat
these communications as a waiver by Horton of the issue, as the Govern-
ment argues we should. When he appeared in court, Horton’s motion for
substitute counsel had already been denied and he had been informed that
his only choices were to either proceed pro se with Speaks as back-up
counsel or be represented by Speaks. Under these circumstances, we con-
clude that Horton preserved a Sixth Amendment claim based on that
denial.
8                      UNITED STATES v. HORTON
during a custodial interview on February 4, 2008. There were
two officers present at the time of Horton’s confession, ATF
Special Agent Fanelly and Raleigh Police Department Officer
Nickel.3 Fanelly was conducting the interview and Nickel was
merely present. At Horton’s first trial, Fanelly testified that he
did not record the interview because ATF agents never record
interviews, he did not know if the interview room was
equipped with recording devices, and he did not know how to
use such devices. Nickel did not testify at the first trial.

   At the second trial, both officers testified that the reason
they did not record their interrogation of Horton was that it
did not relate to a homicide investigation, and the law only
required such recording as part of homicide investigations.4
Fanelly also testified that, at the start of the interview, he "told
[Horton] what [they were] there to talk about, and [Horton]
said he wanted to talk about the — his arrest for having the
gun at — recovered at his girlfriend’s house." (JA 446.)

   On appeal, Horton attaches much significance to the fact
that both juries asked questions regarding his confession. In
the first trial, the jury inquired whether Horton’s statement to
the police was documented. In the second, the jury asked to
"see [a] transcript of the interview . . . if there is one[.]" (JA
521.) Horton posits that the additional explanation offered by
the officers at his second trial, which he contends was false,
tipped the scales in favor of conviction.

  In his motion for new trial, Horton claimed that an investi-
gative police report prepared by R. Miller of the Raleigh
    3
     The two officers’ names are spelled in different ways throughout the
record. We use the spellings the parties adopted before this Court.
   4
     The North Carolina law requiring the recording of interviews related
to a homicide did not take effect until March 1, 2008, after the interview
at issue was conducted, a fact that Horton acknowledges in his brief. Thus,
there is no allegation that, even if he were a homicide suspect and this was
a homicide interview, the interview was required by state law to be
recorded at that time.
                       UNITED STATES v. HORTON                             9
Police Department ("the Miller Report") was Brady evidence
that should have been disclosed prior to trial, but which was
not. According to Horton, the report shows that, by at least
October 9, 2007, the "Raleigh Police Department was, in fact,
conducting a homicide investigation of Horton" and that "Fa-
nelly was, in fact, involved in [that] investigation." (JA 821,
Mot. for New Trial.) Horton argued that he was entitled to a
new trial because the Government never disclosed that report
to him,5 and he "should [have been] able to use [the Miller
Report] to rebut Nickel’s and Fanelly’s testimonies that they
declined to record their 4 February 2008 interview of Horton
on the ground that said interview was not related to a homi-
cide investigation, as well as to impeach Nickel’s and Fanel-
ly’s credibility for testifying to same." (JA 822.)

   Horton contends that, in denying his motion for new trial,
the district court applied the wrong legal standard and thus
abused its discretion.6 He also argues that, applying the proper
standard for Brady violations, he is entitled to a new trial.

   In response, the Government posits that, although the report
itself might not have been disclosed prior to trial, both "the
  5
     The motion included an affidavit from trial counsel, Speaks, in which
he averred that the Government had never provided the report to him, and
that "[a]t no time during my service as defense counsel . . . did I have any
reason to believe that the 4 February 2008 custodial interview of the
defendant that ATF Special Agent Fanelly and Raleigh Police Department
Officer Nickel conducted at the Raleigh Police Department was related to
a homicide investigation." (JA 894.)
   6
     In its order denying the motion, the district court did not apply a
Brady-type analysis. Instead, it analyzed Horton’s motion under the stan-
dards in our decisions in United States v. Bales, 813 F.2d 1289, 1295 (4th
Cir. 1987), and United States v. Custis, 988 F.2d 1355, 1359 (4th Cir.
1993), applicable in analyzing whether newly-discovered evidence
requires a new trial. In conducting its analysis, the district court reasoned
that even if the evidence had been used to impeach the credibility of
Nickel and Fanelly, the evidence was not likely to result in an acquittal.
Horton argues that this was the wrong test, and the Government does not
contest that assertion in its brief.
10                    UNITED STATES v. HORTON
defendant and trial counsel were aware, well before the first
trial, that the defendant was [the] subject of an ongoing homi-
cide investigation at the time he was interviewed on February
4, 2008. (See J.A. 46, 60, 67-69, 72, 82-83.)" (Gov’t Br. at
42.) As the Government notes, at the hearing on Horton’s
motion to suppress, Fanelly testified that he had informed
Horton he was being investigated for a number of crimes,
including "a drug-related homicide" (JA 67), but that Horton
"said he didn’t want to talk about the homicide or the carjack-
ing, that he just wanted to talk about the gun recovery from
August 10th." (JA 69.) Fanelly further testified at the suppres-
sion hearing that he made it "perfectly clear" to Horton that
he (Fanelly) wanted to talk about the homicide, but when
Horton refused to discuss it, Fanelly let him talk about the
August 10, 2007 incident. (JA 72.) So, the fact that Horton
was a homicide suspect at the time of the February 2008 inter-
view was well known to Horton and his counsel at least as
early as the suppression hearing, and certainly before trial.

   The Government further points to the important fact that
Horton’s "trial counsel successfully moved in limine before
both trials to exclude from evidence ‘any reference to the
existence [of other pending charges], as well as any detail or
circumstances surrounding such charges.’" (Gov’t Br. at 44
(alteration in original).) Accordingly, to introduce evidence of
the Miller Report or the mere fact that Horton was a homicide
suspect would have contradicted the district court’s prior rul-
ing on Horton’s own motion in limine. Finally, the Govern-
ment argues that Horton is overstating on appeal the
impeachment value of the Miller Report. The Government’s
arguments are convincing.

     The standard of review here is settled:

       [m]otions for a new trial based on an alleged Brady
       violation are reviewed for abuse of discretion. It is
       an abuse of discretion for the district court to commit
       a legal error—such as improperly determining
                   UNITED STATES v. HORTON                     11
    whether there was a Brady violation—and that
    underlying legal determination is reviewed de novo.
    See United States v. Llamas, 599 F.3d 381, 391 (4th
    Cir. 2010) (quoting United States v. Delfino, 510
    F.3d 468, 470 (4th Cir. 2007) ("A district court
    abuses its discretion when it commits an error of
    law.")).

United States v. Wilson, 624 F.3d 640, 660-61 n.24 (4th Cir.
2010). As we have noted, the district court applied the wrong
legal standard to Horton’s claim, see supra at note 6, but the
record before us is fully developed such that we can address
Horton’s argument as to an alleged Brady violation de novo.
Applying the proper legal standard, we conclude that Horton
has not established that a Brady violation occurred or that he
is entitled to a new trial.

  In Wilson, we set forth the basic framework of analysis for
a new trial motion based on a Brady violation:

    In Brady, the Supreme Court held "that the suppres-
    sion by the prosecution of evidence favorable to an
    accused upon request violates due process where the
    evidence is material either to guilt or to punishment,
    irrespective of the good faith or bad faith of the pros-
    ecution." 373 U.S. at 87. In order to prove that the
    Government’s failure to tender certain evidence con-
    stitutes a Brady violation, the burden rest[s] on [the
    defendant] to show that the undisclosed evidence
    was (1) favorable to him either because it is exculpa-
    tory, or because it is impeaching; (2) material to the
    defense, i.e., "prejudice must have ensued"; and (3)
    that the prosecution had materials and failed to dis-
    close them. United States v. Stokes, 261 F.3d 496,
    502 (4th Cir. 2001).

624 F.3d at 660-61.
12                     UNITED STATES v. HORTON
   We further explained the relevant concepts as follows: "Ev-
idence is ‘exculpatory’ and ‘favorable’ if it ‘may make the
difference between conviction and acquittal’ had it been ‘dis-
closed and used effectively.’ United States v. Bagley, 473
U.S. 667, 676 (1985). Evidence is ‘material’ if it is ‘likely to
have changed the verdict.’ Moseley v. Branker, 550 F.3d 312,
318 (4th Cir. 2008)." Wilson, 624 F.3d at 661; see Winston v.
Kelly, 592 F.3d 535, 556 (4th Cir. 2010) ("[T]he materiality
element of a Brady claim requires a collective assessment of
whether introduction of the exculpatory evidence might have
affected the outcome of the trial.").

   Applying this test here, we conclude that Horton cannot
satisfy the second factor, i.e., that introduction of the exculpa-
tory evidence might have affected the outcome of the trial; we
thus need not address the first or third factors.7 Importantly,
we agree with the Government that the Miller Report would
have had a minimal impact, if any, on the credibility of the
officers. This is so because the officers had a plausible expla-
nation, consistent with their testimony and the Miller Report,
that renders the report largely insignificant. That is, Fanelly
testified at the suppression hearing that Horton was a suspect
in a homicide, but that the interview itself did not relate to the
homicide, because Horton repeatedly told the officers he did
not want to talk about the homicide. There is nothing in
Fanelly’s explanation that is inconsistent with the Miller
Report’s conclusion that Horton was brought in as a homicide
suspect, but then (from the start of the interview, when Horton
refused to be interviewed about anything other than the gun
possession incident on August 10, 2007), that interview was
not related to the homicide investigation.

   Indeed, Horton’s own motion in limine was at least one
factor that prevented Fanelly from providing a fuller explana-
  7
    Although it used the different Custis/Bales analysis, see supra n.6, the
district court properly based its denial of Horton’s motion for new trial on
the lack of effect on the outcome of the trial, as well.
                      UNITED STATES v. HORTON                           13
tion to the jury.8 Because Fanelly was not permitted to state
that Horton was being investigated for a homicide, he could
not explain before the jury that the interview did not relate to
a homicide because Horton refused to discuss it and instead
would only talk about the gun possession charge on August
10, 2007. Fanelly was able to explain that fact fully at the sup-
pression hearing (when the jury was not present), and gave as
full an explanation as he could to the jury at the second trial,
without violating Horton’s in limine motion. At argument
before this Court, Horton’s counsel admitted that, if the Miller
Report had been available to trial counsel and he had used it
for impeachment purposes, the jury would have learned that
Horton was a suspect in a homicide, evidence that Horton
obviously believed was prejudicial, or he would not have
moved in limine to exclude it. Given this trade-off, we think
it highly unlikely that, if counsel elected to use it as impeach-
ment evidence, this evidence would have changed the out-
come of Horton’s trial. It borders on the disingenuous for
Horton to claim the benefits of the granted motion in limine
at trial, but now seek to eschew it on appeal.

   Moreover, there was strong evidence against Horton other
than his confession, including the testimony of his girlfriend
at the time of the incident. The Government also introduced
into evidence the spent shell casings and the gun itself that
were recovered from the ground outside Ms. Bryant’s home
and from inside her home, respectively. Additionally, the offi-
cer who initially reported to the scene testified that he
observed a bullet hole in Ms. Bryant’s car, and that Ms. Bry-
ant appeared "a little shaken and upset" when he arrived. (JA
402.) Thus, the credibility of the officers as to Horton’s con-
fession, while important to the case against him, was only part
of the case presented to the jury. In short, no Brady violation
occurred and Horton is not entitled to a new trial.
  8
    It is also possible that it would have violated Horton’s right against
self-incrimination under Miranda v. Arizona, 384 U.S. 436 (1966) for
Agent Fanelly to testify about Horton’s refusal to talk about the homicide.
14                      UNITED STATES v. HORTON
                 III.   Challenges to the Sentence

   Horton also appeals his sentence, challenging on appeal the
district court’s application of the murder cross-reference. He
raises four separate claims of error (three of which relate to
the application of the cross-reference), but because of our
holding, we need only address two.9 The first claim we
address is Horton’s argument that the district court erred in its
factual finding that he was present or involved in the home
invasion and robbery during which the murder occurred. The
second is his argument that the district court misapplied the
Guidelines and erred in concluding that the murder was "rele-
vant conduct" to the offense of conviction. We address each
of these challenges in turn.

   In doing so, we are mindful of our role, which is that "[w]e
review a sentence for reasonableness, applying an abuse of
discretion standard." United States v. Susi, 674 F.3d 278, 282
(4th Cir. 2012) (citing Gall v. United States, 552 U.S. 38, 49
(2007)).

      In conducting that review, [we] first "ensure[ ] that
      the district court committed no significant procedural
      error, such as failing to calculate (or improperly cal-
      culating) the Guidelines range, treating the Guide-
      lines as mandatory, failing to consider the § 3553(a)
      factors, selecting a sentence based on clearly errone-
  9
    In his third challenge to the application of the murder cross-reference,
Horton maintains that if the district court properly applied the Guidelines
in this case and if the Guidelines are so broad as to allow the use of an
uncharged, unrelated murder to dramatically increase Horton’s offense
level, then the Guidelines violate Horton’s Sixth Amendment rights. Hor-
ton’s fourth contention, unrelated to the murder cross-reference, is that the
district court erred both in treating the advisory Guidelines as mandatory
and in failing to adequately consider the 18 U.S.C. § 3553(a) factors.
   Because we conclude that the Guidelines do not allow the application
of the murder cross-reference here, and because we remand for resentenc-
ing, we do not address these arguments.
                     UNITED STATES v. HORTON                    15
      ous facts, or failing to adequately explain the chosen
      sentence . . . ." [Gall, 552 U.S.] at 51. If we find no
      significant procedural error, then we consider the
      substantive reasonableness of the sentence imposed
      ....

Id.

   In this case, because we conclude that the district court
committed a significant procedural error, we do not reach the
substantive reasonableness of Horton’s sentence. See United
States v. Carter, 564 F.3d 325, 328 (4th Cir. 2009) (appellate
court can consider the substantive reasonableness of a sen-
tence "[i]f, and only if" it "find[s] the sentence procedurally
reasonable"); id. at 330 n.4 ("Having found the sentence pro-
cedurally unreasonable, . . . we cannot review the sentence for
substantive reasonableness.").

         A.   Additional Background as to Sentencing

   The presentence report ("PSR") prepared by the Probation
Office first discussed the facts of the only offense charged in
the indictment and the only offense of which Horton was con-
victed—the August 10, 2007 events at Ms. Bryant’s home.
Nonetheless, the bulk of the sentencing proceeding was
devoted to testimony regarding a second incident, which the
PSR determined—and the district court agreed—was "rele-
vant conduct."

   According to the PSR, this second incident occurred on
August 17, 2007, one week after Horton possessed the firearm
and fired the shots outside Ms. Bryant’s home. On August 17,
five adults and five children were present in an apartment in
Raleigh when one of the adults, Charmeka Harris, opened the
door in response to knocking. Three masked individuals, at
least two of whom were armed, then barged into the apart-
ment and robbed the occupants of various belongings at gun-
point. Upon entering the residence, one of the assailants shot
16                    UNITED STATES v. HORTON
Ms. Harris in the stomach with a sawed-off shotgun and she
later died from the injury.

   There were numerous inconsistencies in the victim and wit-
ness statements regarding various aspects of the home inva-
sion, including how many assailants participated, how many
of them were armed, and what they looked like, to the extent
that they were not disguised. The attempts by victims to iden-
tify the assailants through subsequent line-ups were unsuc-
cessful and the shotgun was never recovered.

   In addition to the victims and some non-victim witnesses at
the apartment complex, several other individuals provided
statements to authorities concerning their knowledge of the
robbery/murder. Most of these were from persons who indi-
cated they had heard the alleged perpetrators of the robbery
discussing it, or heard second-hand of comments made by
them. Some of these statements implicated Horton, either as
being involved in the robbery or being the shooter, and others
indicated that he was not present or involved and instead iden-
tified others as the perpetrators. Ultimately, the police investi-
gation into the incident identified Horton and four others
whom the investigators believed were participants in the rob-
bery.10

     Based on the foregoing, the PSR concluded that

       the preponderance of the evidence supports that
       [Horton] possessed a firearm during the rob-
       bery/home invasion on August 17, 2007, and he is
       responsible for the murder of Charmeka Harris. As
       such, he possessed a firearm as a convicted felon in
       connection with another felony offense, First Degree
  10
    A grand jury for Wake County, North Carolina returned indictments
against Horton and three other individuals, charging them with the murder
of Ms. Harris on August 17, 2007. This state court murder charge against
Horton was dismissed shortly after his sentencing in this case.
                   UNITED STATES v. HORTON                    17
    Murder, and a cross-reference to the substantive
    offense is warranted.

(JA 935, ¶ 5.) Accordingly, the PSR computed and explained
Horton’s base offense level as follows:

    The United States Sentencing Commission Guide-
    line for violation of 18 U.S.C. § 922(g) is found in
    2K2.1; however, 2K2.1(c)(1) provides that if the
    defendant used or possessed any firearm or ammuni-
    tion in connection with the commission or attempted
    commission of another offense . . . apply 2X1.1 in
    respect to that other offense, if the resulting offense
    level is greater than that determined under 2K2.1. If
    death resulted, apply the most analogous offense
    guideline from Chapter 2, Part A, Subpart 1, if the
    resulting offense level is greater than that determined
    above. Pursuant to 2X1.1(a), the base offense level
    is determined from the guideline for the substantive
    offense, plus any adjustments from such guideline
    for any intended offense conduct that can be estab-
    lished with reasonable certainty. [Horton] possessed
    a firearm in connection with the robbery on August
    17, 2010. As Horton is responsible for the shooting
    death which occurred during the robbery, the guide-
    line for First Degree Murder ([USSG §] 2A1.1) has
    been used and calls for a base offense level of 43.

(JA 947, ¶ 46.)

  At sentencing, the district court heard testimony from two
police detectives who had investigated the home invasion and
shooting concerning their investigation and the various state-
ments they received. The court ultimately concluded that the
preponderance of the evidence supported the finding that Hor-
ton possessed a firearm during the August 17, 2007 rob-
bery/home invasion.
18                      UNITED STATES v. HORTON
   The district court further found the August 17 murder was
relevant conduct to the August 10 instant offense, which led
to the significant increase in Horton’s base offense level
based on the cross-referencing provision. The district court
thus adopted the PSR’s computation of Horton’s base offense
level, which used the Guideline for First Degree Murder
(USSG § 2A1.1) instead of the lower offense level for a sim-
ple felon-in-possession charge. (Id. at 947, ¶ 46.) This
resulted in a base offense level of 43 instead of the lower
offense level applicable to § 922(g)(1) violations.11

   Horton had 15 criminal history points, establishing a crimi-
nal history category of VI. He was also an armed career crimi-
nal, which provides an independent ground for establishing a
criminal history category of VI. The advisory Guidelines
range, as determined by the district court, called for life
imprisonment, and the applicable statutory provision (18
U.S.C. § 924(e)) required a mandatory minimum of not less
than 15 years. The district court imposed a sentence of life
imprisonment.

                   B.    Factual Finding as Error

  In assessing whether a district court properly calculated the
Guidelines range, including its application of any sentencing
enhancements, this Court "review[s] the district court’s legal
conclusions de novo and its factual findings for clear error."
United States v. Layton, 564 F.3d 330, 334 (4th Cir. 2009).
  11
    There is apparently some dispute as to what Horton’s offense level
would have been had the cross-reference for murder not been applied. The
Government contends that the total offense level would have been 34 and
Horton’s advisory Guidelines range would have been 262 to 327 months’
imprisonment. In his sentencing memorandum before the district court,
however, Horton argued that his total offense level should have been 33,
with an advisory Guidelines range of 235 to 293 months. Because it
applied the murder cross-reference, the district court did not need to
resolve this dispute. Since we are remanding with instructions not to apply
the murder cross-reference, however, this is an issue for the district court
to address in the first instance.
                       UNITED STATES v. HORTON                            19
   We first address Horton’s contention that the district court
clearly erred in finding, as a factual matter and by a prepon-
derance of the evidence, that Horton was involved in the
August 17, 2007 robbery and responsible for the murder of
Ms. Harris. As noted, we review this factual finding only for
"clear error," which is a very deferential standard of review,
allowing us to reverse only if we are "left with a definite and
firm conviction that a mistake has been committed." F.C.
Wheat Mar. Corp. v. United States, 663 F.3d 714, 723 (4th
Cir. 2011). While there was some conflicting evidence on the
point, the district court heard extensive testimony from two
agents regarding the investigation into the murder of Ms. Har-
ris and there was sufficient evidence to support a finding, by
a preponderance of the evidence, that Horton committed the
murder. Thus, to the extent that Horton challenges the district
court’s factual finding that he committed the murder as
unsupported by reliable evidence, he has not shown error
under the applicable standard of review.12
   12
      We respectfully disagree with our colleague’s conclusion as to Section
III-B. We addressed Horton’s arguments in their logical order. If we had
concluded that the district court clearly erred in its factual determination
regarding the August 17, 2007 murder, the more complicated issue of the
murder cross-reference’s applicability would not have been reached. Both
this Court and other appellate courts routinely affirm factual findings rele-
vant to sentencing decisions, even when remanding for resentencing based
on other errors. See, e.g., United States v. Llamas, 599 F.3d 381, 388-90
(4th Cir. 2010) (reversing and remanding where district court erred in
applying a "vulnerable victim" adjustment without an adequate explana-
tion, but affirming the application of an aggravating role adjustment
because it was not clearly erroneous); United States v. Manatau, 647 F.3d
1048, 1057 & n.4 (10th Cir. 2011) (vacating sentence for a new determi-
nation of intended loss, but finding district court properly applied separate
enhancement for the number of victims); United States v. Flores, 640 F.3d
638, 644-45 (5th Cir. 2011) (remanding for resentencing because a leader-
ship role enhancement was based on erroneous facts, but affirming
obstruction of justice enhancement); United States v. Newman, 614 F.3d
1232, 1238-39 (11th Cir. 2010) (reversing and remanding for resentencing
because district court erred in applying enhancement for "extensive scope"
of offense, but affirming district court’s application of an enhancement for
20                      UNITED STATES v. HORTON
   That fact alone, however, does not establish the propriety
of applying the cross-reference. As noted, Horton also argues
that, even assuming the district court’s factual finding that he
committed the murder was proper, the application of the
cross-reference is nonetheless improper. We turn to this con-
tention next.

interfering with the administration of justice); United States v. Williams,
527 F.3d 1235, 1252 (11th Cir. 2008) (remanding for resentencing
because sentencing adjustments for aggravated role and for abuse of trust
were unjustified, but nonetheless affirming the district court’s finding that
the defendant obstructed justice).
   Moreover, while we have concluded that the murder of Ms. Harris is
irrelevant to determining the appropriate advisory Guidelines range, it is
up to the district court to decide whether to take it into consideration at
sentencing pursuant to the court’s § 3553(a) determination. See Gall, 552
U.S. at 49-50 ("[t]he Guidelines are not the only consideration . . . . [A]fter
giving both parties an opportunity to argue for whatever sentence they
deem appropriate, the district judge should then consider all of the
§ 3553(a) factors to determine whether they support the sentence
requested by a party."); United States v. Hernandez-Villanueva, 473 F.3d
118, 122 (4th Cir. 2007) (district court is required to "determine whether
a sentence within [the advisory] range . . . serves the factors set forth in
§ 3553(a) and, if not, select a sentence [within statutory limits] that does
serve those factors.") (citation omitted); United States v. Grubbs, 585 F.3d
793, 799, 802 (4th Cir. 2009) (after Booker, "[s]entencing courts continue
to exercise their long-standing authority to hear the evidence, and consider
any evidence at sentencing that ‘has sufficient indicia of reliability[,]’"
including evidence of uncharged conduct). Of course, if the district court
imposed an above-Guidelines sentence on remand, it would be required to
provide sufficient explanation for its chosen sentence and any "major"
departure would require a "more significant justification than a minor"
one. Gall, 552 U.S. at 50.
   Finally, we disagree with our colleague’s statement that there is "no
authority" for the district court to decline to revisit this factual issue at
resentencing. Post at 32. In fact, this Court has squarely held that the dis-
trict court would be "well within its authority to decline to revisit every
sentencing issue on remand, unless the mandate indicates otherwise or the
interrelationship of sentencing components makes it advisable to do so."
Susi, 674 F.3d at 286; id. at 284 ("[n]othing in Pepper [v. United States,
131 S. Ct. 1229 (2011)] . . . requires the district court to reconsider every
component of the sentencing decision during resentencing").
                   UNITED STATES v. HORTON                   21
          C.   Application of the Cross-Reference

   As noted above, the PSR recommended—and the district
court concluded—that the August 17, 2007 robbery and mur-
der were relevant conduct for sentencing purposes. In assess-
ing the propriety of that determination, three provisions of the
Sentencing Guidelines are pertinent: (1) USSG § 2K2.1(c)(1)
("the Cross-Reference Provision"); (2) USSG § 1B1.3 ("the
Relevant Conduct Guideline"); and (3) USSG § 3D1.2 ("the
Grouping Guideline"). We now discuss the interrelation of
these provisions in determining whether the district court
erred in its Guidelines determination.

   The offense level for a violation of 18 U.S.C. § 922(g)(1),
the offense of conviction here, is established under USSG
§ 2K2.1. Subsection (c) of this Guideline, the Cross-
Reference Provision, states in relevant part:

    If the defendant used or possessed any firearm or
    ammunition in connection with the commission or
    attempted commission of another offense, or pos-
    sessed or transferred a firearm or ammunition with
    knowledge or intent that it would be used or pos-
    sessed . . . in connection with another offense, . . .
    [and] (B) if death resulted, [the court should apply]
    the most analogous offense guideline from Chapter
    Two, Part A, Subpart 1 (Homicide), if the resulting
    offense level is greater than that determined above.

USSG § 2K2.1(c)(1).

   Applicability of the Cross-Reference Provision, in turn,
depends on whether the cross-referenced offense constitutes
relevant conduct under the Relevant Conduct Guideline. See
USSG § 1B1.3(a) (cross-references are to be determined on
the basis of relevant conduct unless otherwise specified);
United States v. Pauley, 289 F.3d 254, 258 (4th Cir. 2002),
vacated in non-relevant part on reh’g, 304 F.3d 335 (4th Cir.
22                  UNITED STATES v. HORTON
2002) (per curiam), ("Under the scheme created by the
[USSG], whether a particular cross-reference should be
applied depends on whether the conduct to which the cross-
reference refers is ‘relevant conduct’" as defined in the Rele-
vant Conduct Guideline). Put differently, only conduct that
also falls within the scope of the Relevant Conduct Guideline
can be the subject of the Cross-Reference Provision. Accord-
ingly, we must review the Relevant Conduct Guideline to
determine whether the murder here falls within its scope.

   The Relevant Conduct Guideline treats as relevant conduct,
including for cross-referencing purposes, the following:

     [(a)(1)] all acts and omissions committed, aided,
     abetted, counseled, commanded, induced, procured,
     or willfully caused by the defendant . . . that
     occurred during the commission of the offense of
     conviction, in preparation for that offense, or in the
     course of attempting to avoid detection or responsi-
     bility for that offense;

     [(a)(2)] solely with respect to offenses of a character
     for which § 3D1.2(d) [the "Grouping Guideline"]
     would require grouping of multiple counts, all acts
     and omissions described in subdivisions (1)(A) and
     (1)(B) above that were part of the same course of
     conduct or common scheme or plan as the offense of
     conviction; [and]

     [(a)(3)] all harm that resulted from the acts and
     omissions specified in subsections (a)(1) and (a)(2)
     above, and all harm that was the object of such acts
     and omissions . . . .

USSG § 1B1.3.

  As is obvious from its text, Subsection (a)(1) of the Rele-
vant Conduct Guideline requires a closer connection between
                       UNITED STATES v. HORTON                            23
the acts and omissions committed and the offense of convic-
tion than does Subsection (a)(2), which encompasses a
broader group of acts. United States v. Johnson, 347 F.3d 635,
640 (7th Cir. 2003) ("Subsection (a)(2) allows a court to con-
sider a broader range of conduct than does the trailing clause
of (a)(1). USSG § 1B1.3, cmt. background."). As a counter-
balance to this broader scope, however, Subsection (a)(2) has
a threshold limitation on its applicability, i.e., it is applicable
"solely with respect to offenses of a character for which [the
Grouping Guideline] would require grouping of multiple
counts." USSG § 1B1.3(a)(2).

   Notably, the Government does not contend that the August
17, 2007 robbery and murder would fall within Subsection
(a)(1) of the Relevant Conduct Guideline.13 Thus, we look
here only to whether the murder falls within Subsection (a)(2)
which, by its express terms, requires reference to the Group-
ing Guideline, USSG § 3D1.2.

   The Guidelines Commentary explains the interplay and
purpose of the reference to the Grouping Guideline in Subsec-
tion (a)(2) as follows:

     Subsection (a)(2) provides for consideration of a
     broader range of conduct with respect to one class of
     offenses, primarily certain property, tax, fraud and
     drug offenses for which the guidelines depend sub-
     stantially on quantity, than with respect to other
     offenses such as assault, robbery and burglary. The
     distinction is made on the basis of § 3D1.2(d), which
     provides for grouping together (i.e., treating as a sin-
     gle count) all counts charging offenses of a type cov-
     ered by this subsection. . . .
   13
      Indeed, there is no basis apparent from the record for concluding that
the August 17, 2007 offense was an act that occurred "during the commis-
sion of the offense of conviction, in preparation for it, or in the course of
attempting to avoid detection or responsibility for the offense of convic-
tion," as required for Subsection (a)(1) to apply.
24                  UNITED STATES v. HORTON
        Subsections (a)(1) and (a)(2) adopt different rules
     because offenses of the character dealt with in sub-
     section (a)(2) (i.e., [groupable offenses under the
     Grouping Guideline]) often involve a pattern of mis-
     conduct that cannot readily be broken into discrete,
     identifiable units that are meaningful for purposes of
     sentencing. . . .

USSG § 1B1.3, cmt. background.

   For purposes of this opinion, two aspects of the Grouping
Guideline are significant: (1) it requires that felon-in-
possession offenses be grouped; and (2) it specifically forbids
the grouping of homicide offenses and other violent offenses.
See USSG § 3D1.2(d) (grouping is required for offenses cov-
ered by § 2K2.1 and excluded from grouping are "all offenses
in Chapter Two, Part A (except § 2A3.5)," which includes the
Guideline for murder, § 2A1.1). While the parties agree on
these two principles, clear from the text of the Grouping
Guideline itself, they differ on how to apply these principles
in this case. There is also a circuit split as to how to properly
apply the Grouping Guideline when determining cross-
references for murder or other violent offenses.

   The Government’s explanation as to why the murder cross-
reference should apply (and the rationale in the PSR adopted
by the district court) can be stated as follows. First, the defen-
dant’s unlawful possession of a firearm on August 17, 2007
during the robbery and murder, is groupable with the offense
of conviction because both are felon-in-possession offenses.
Thus, according to the Government, the procedural trigger of
groupability, necessary for Subsection (a)(2) of the Relevant
Conduct Guideline to apply, is satisfied. Second, the substan-
tive requirement in Subsection (a)(2) that the two offenses be
"part of the same course of conduct or common scheme or
plan" is also satisfied. Third, the murder which occurred dur-
ing the August 17, 2007 relevant conduct offense, is likewise
relevant conduct pursuant to Subsection (a)(3) of the Relevant
                      UNITED STATES v. HORTON                           25
Conduct Guideline, which includes "all harm that resulted
from the acts . . . specified in [Subsection (a)(2)]."

   Not surprisingly, Horton disagrees. He argues instead that
the pertinent offenses for determining groupability are the
offense of conviction (the August 10 felon-in-possession
charge) and the offense for which the cross-reference is being
applied, which in this case is murder. Because a murder
offense is specifically not subject to grouping, Horton con-
tends that the procedural trigger for application of Subsection
(a)(2) of the Relevant Conduct Guideline—i.e., groupability
of the two offenses—is not satisfied. Accordingly, Subsection
(a)(2) cannot be utilized to render the August 17, 2007 inci-
dent relevant conduct. And, as noted, the Government does
not argue that the murder is relevant conduct under Subsec-
tion (a)(1).14

   There is a circuit split in the threshold issue as to whether
only the offense of conviction need be a groupable offense or
whether both the offense of conviction and the relevant con-
duct offense (the cross-referenced offense) must be groupable
offenses in order to apply Subsection (a)(2). Notably, all but
one of the circuits to have squarely addressed the issue have
adopted Horton’s view that both must be groupable. See, e.g.,
United States v. Williams, 431 F.3d 767, 772-73 & n.9 (11th
Cir. 2005) (concluding that where conviction was for a viola-
tion of 18 U.S.C. § 922(g), the district court erred in utilizing
an assault with a different firearm as relevant conduct,
because assault is excluded from being grouped, and thus "the
definition of relevant conduct found in § 1B1.3(a)(2) is not
available to the Government"); United States v. Settle, 414
  14
    Horton argues, alternatively, that even if the Government is correct
that the offenses that must be grouped are the two separate instances of
Horton possessing a gun as a felon, the second incident (including the
murder) is not relevant conduct because it does not satisfy Subsection
(a)(2)’s requirement that it be "part of the same course of conduct or com-
mon scheme or plan as the offense of conviction." In light of our holding,
we do not reach this issue.
26                  UNITED STATES v. HORTON
F.3d 629, 632 n.2 (6th Cir. 2005) (attempted murder is not
groupable and thus could not be relevant conduct under Sub-
section (a)(2) in case where charge of conviction was felon-
in-possession of a firearm); United States v. Jones, 313 F.3d
1019, 1023 & n.3 (7th Cir. 2002) (although holding that the
Cross-Reference Provision in § 2K2.1 was appropriately
applied to a murder that was relevant conduct under Subsec-
tion (a)(1), observing the murder would not be relevant con-
duct under Subsection (a)(2) because "the homicide charge is
specifically excluded" from the Grouping Guideline); United
States v. Levario-Quiroz, 161 F.3d 903, 906 (5th Cir. 1998)
(in applying the Cross-Reference Provision, defendant’s acts
of assault with attempt to commit murder and attempted mur-
der were not "relevant conduct" under Subsection (a)(2)
because, although they were part of the same course of con-
duct as the offense of conviction, "they were not offenses of
a character for which [USSG §] 3D1.2(d) would require
grouping"). But see United States v. Kulick, 629 F.3d 165,
170-71 & n.4 (3d Cir. 2010) (concluding that only the offense
of conviction need be subject to grouping).

  In Jones, the Seventh Circuit addressed—and rejected—the
precise analysis proposed by the Government here:

     It was additionally argued that consideration of the
     armed robbery/felony murder as relevant conduct
     was appropriate under guideline § 1B1.3(a)(2),
     which includes within its definition of "relevant con-
     duct" "all acts and omissions . . . that were part of
     the same course of conduct or common scheme or
     plan as the offense of conviction," but only with
     respect to offenses for which grouping under
     § 3D1.2(d) would be required. Grouping would not
     be required in this case-in fact, grouping of the felon
     in possession count with the homicide charge is spe-
     cifically excluded from the operation of
     § 3D1.2(d)—rendering § 1B1.3(a)(2)’s relevant-
     conduct definition inapplicable here.
                         UNITED STATES v. HORTON                           27
313 F.3d at 1023 n.3.15 As noted, the other circuits cited above
agree.

   The Third Circuit has held to the contrary. Kulick, 629 F.3d
at 170-71 & nn.4-5 (holding pursuant to the binding prior
panel decision of Jansen v. United States, 369 F.3d 237, 248
(3d Cir. 2004), Subsection (a)(2) is applicable "when the
offense of conviction is a groupable offense, regardless of the
nature of the alleged relevant conduct"). Notably, however,
the Kulick court embraced its holding with little enthusiasm,
instead stating that, if it were not bound by Jansen, "an argu-
ment might be made that we should not apply [Subs]ection
(a)(2) on these facts . . . ." Id. at 170 n.4. The Kulick court
also "le[ft] for another day whether to recommend en banc
consideration of whether Jansen’s effect should be limited to
drug offenses or to those cases in which the offense of convic-
tion has a higher offense level than the alleged relevant con-
duct." Id.

   Now squarely faced with the same issue as our sister circuits,16
  15
      In Jones, the defendant had used the same firearm he was convicted
of possessing during an armed-robbery and felony-murder incident four
days prior to the offense of conviction. Although rejecting Subsection
(a)(2) as a basis for finding the earlier robbery/murder incident "relevant
conduct," the Jones Court nonetheless upheld application of the murder
cross-reference under Subsection (a)(1) of the Relevant Conduct Guide-
line, concluding that the armed robbery/felony murder "occurred during
the commission of the offense of conviction." 313 F.3d at 1021, 1023 &
n.3.
   16
      The Government contends that this Circuit adopted the contrary posi-
tion in Pauley, but we disagree. Instead, we conclude that our circuit has
not spoken directly on this issue. Pauley held that, in a drug conspiracy
case, a murder cross-reference from the drug distribution Guideline,
§ 2D1.1(d), was appropriate under Subsection (a)(2). In so doing, the court
explained:
       By its terms, §1B1.3(a)(2) applies only to offenses to which [the
       Grouping Guideline] would require the grouping of multiple
       counts. . . . [The Grouping Guideline] also lists guidelines to
28                     UNITED STATES v. HORTON
we agree with the conclusions of the Fifth, Sixth, Seventh,
and Eleventh Circuits and hold that Subsection (a)(2) of the

     which the section applies. The offense level in drug distribution
     cases is, of course, determined on the basis of quantity, and
     § 2D1.1—the guideline containing the murder cross-
     reference—is specifically listed as a guideline to which [the
     Grouping Guideline] applies. Accordingly, the district court
     properly looked to § 1B1.3(a)(2) in determining the scope of "rel-
     evant conduct."
289 F.3d at 258-59.
   Pauley is easily distinguishable on its facts. There, the offense of con-
viction was a drug conspiracy, and the defendant was involved in a series
of four home robberies where defendant and his drug associates, usually
armed with handguns, stole drugs and/or money from the homes of other
drug dealers. During one of the robberies, Pauley shot and killed two resi-
dents of the home. 289 F.3d at 256-58. Based on the way the district court
ruled and the parties argued the case, the Pauley court analyzed the cross-
reference under Subsection (a)(2) of the Relevant Conduct Guideline. But
the murders there likely would have been relevant conduct under Subsec-
tion (a)(1).
   Moreover, a review of the briefs in Pauley reveals that the defendant
never argued that murder had to be a groupable offense in order for the
cross-reference to apply. Instead, both the parties and the Pauley court
assumed that only the offense of conviction need be groupable and thus
was not required to rule on the issue. The parties framed their arguments
only as addressing whether the murder was "part of the same course of
conduct or common scheme or plan" so as to render Subsection (a)(2) of
the Relevant Conduct Guideline applicable. The defendant there simply
did not argue, as Horton does here, that Subsection (a)(2) was inapplicable
because murder was not a groupable offense. Thus, nothing in Pauley
directly addressed the issue now before us. See Brecht v. Abrahamson, 507
U.S. 619, 631 (1993) ("[S]ince we have never squarely addressed the
issue, and have at most assumed [it], we are free to address the issue on
the merits."); Webster v. Fall, 266 U.S. 507, 511 (1925) ("Questions
which merely lurk in the record, neither brought to the attention of the
court nor ruled upon, are not to be considered as having been so decided
as to constitute precedents."); Fernandez v. Keisler, 502 F.3d 337, 343 n.2
(4th Cir. 2007) ("We are bound by holdings, not unwritten assumptions.");
Getty Petroleum Corp. v. Bartco Petroleum Corp., 858 F.2d 103, 113 (2d
Cir. 1988) ("a sub silentio holding is not binding precedent").
                   UNITED STATES v. HORTON                    29
Relevant Conduct Guideline is applicable only when both the
offense of conviction and the relevant conduct offense are
capable of grouping. See USSG § 1B1.1 cmt. n.1(H) (defining
"offenses" to "mean[s] the offense of conviction and all rele-
vant conduct.")

   We further reject the Government’s argument that the rele-
vant conduct "offense" is the second felon in possession
offense occurring on August 17. As we have held above and
as applied in the context of cross-references, both the offense
of conviction and the cross-referenced offense must be group-
able. Contrary to the Government’s contention, the relevant
conduct offense here is murder, because it was the murder
offense and its Guideline that was used to set Horton’s
offense level, and it was the murder that the district court
treated as "relevant conduct." As the Eleventh Circuit
cogently explained in Williams:

    The Government also makes an argument that it is
    not the assault that would be grouped but rather the
    firearm used in the assault. This is not correct:
    § 2K2.1(c)(1) refers to another offense in which a
    firearm was used. Therefore, it is the other offense
    which must be subject to the rules regarding group-
    ing because it is the assault guideline that is used to
    calculate the offense level.

431 F.3d at 772 n.9. Similarly, here it is the murder that must
be groupable for Subsection (a)(2) to apply "because it is the
[murder] guideline that is used to calculate the offense level,"
and it clearly is not. See id.; Settle, 414 F.3d at 632 n.2;
Levario-Quiroz, 161 F.3d at 906; Jones, 313 F.3d at 1023 n.3.

   The Government errs in treating the felon-in-possession
offense as the relevant conduct offense in order to bring it
within the Grouping Guideline because that analysis ignores
how the cross-reference operates. Tellingly, the cross-
reference does not affect the offense level by, for example,
30                     UNITED STATES v. HORTON
adding a second firearm possession to the offense characteris-
tics. Instead, it applies the offense level for murder. Because
murder is excluded from the grouping rules, Subsection (a)(2)
is not available to the Government to utilize the murder as the
relevant conduct.17

   For the foregoing reasons, we conclude the district court
erred in applying the murder cross-reference under Subsection
(a)(2). We therefore vacate Horton’s sentence and remand for
resentencing.18

                           IV.     Conclusion

   For the reasons set forth above, we affirm Horton’s convic-
tion, vacate his sentence, and remand for resentencing consis-
tent with this opinion.




  17
      Had the Government charged Horton and obtained a conviction for his
August 17 possession of the firearm used in the robbery and murder of
Ms. Harris, that murder likely would have qualified as relevant conduct at
sentencing on the August 17 felon-in-possession charge under Subsection
(a)(1) of the Relevant Conduct Guideline. See United States v. Wright, 594
F.3d 259, 267-69 (4th Cir. 2010).
   18
      We emphasize that our holding is a narrow one, and should not be
read to limit the Cross-Reference Provision only to charged conduct or
conduct for which a conviction is obtained. Grubbs, 585 F.3d at 799 ("[a]
sentencing court may consider uncharged and acquitted conduct in deter-
mining a sentence, as long as that conduct is proven by a preponderance
of the evidence"). Nor do we hold that the Cross-Reference Provision is
limited to conduct related to the specific weapon or weapons identified in
an indictment. For example, several circuits have recognized that the
Cross-Reference Provision refers to the use of "any firearm" and, as a
result, the provision is not limited to just the firearm that was involved in
the offense of conviction. See 2K2.1(c)(1); Williams, 431 F.3d at 770-771
("join[ing] the Eighth and Tenth Circuits to hold that ‘any firearm’ truly
means any firearm" and thus § 2K2.1(c)(1) can apply to firearms not
named in the indictment").
                   UNITED STATES v. HORTON                    31
                                        AFFIRMED IN PART,
                                         VACATED IN PART,
                                    AND REMANDED IN PART

DAVIS, Circuit Judge, concurring in part and concurring in
the judgment:

   I concur in most of the majority opinion and in the judg-
ment. I agree there are no grounds for vacating the conviction,
for the reasons the majority explains. I also agree that the dis-
trict court procedurally erred in cross-referencing the August
17, 2007, murder of Charmeka Harris. The district court
should not have, and cannot on remand, rely on the Harris
murder to increase Horton’s advisory term of imprisonment
under the Sentencing Guidelines. That conclusion, in my
view, renders it entirely unnecessary and inappropriate to con-
sider, as the majority does in section III-B, Horton’s alterna-
tive ground for challenging his life sentence: whether "the
district court clearly erred in finding, as a factual matter and
by a preponderance of the evidence, that Horton was involved
in the August 17, 2007 robbery and responsible for the mur-
der of Ms. Harris." Maj. Op. at 19.

                               I.

   The upshot of our conclusion that the Harris murder cannot
be cross-referenced is this: the Sentencing Commission has
determined that the courts generally should not tack on pun-
ishment for crimes such as the Harris murder to sentences for
crimes such as Horton’s prohibited possession of the .22 rifle.
In essence the Commission is telling us that Horton should
only be punished for his alleged involvement in the Harris
murder if the government can (and does) prove, to a jury and
beyond a reasonable doubt, that Horton committed the mur-
der. Indeed, the State of North Carolina apparently had
intended to take that usual route — that is, until the district
court in this case elected, erroneously, to invoke the murder
cross-reference and sentence Horton to life imprisonment. At
32                    UNITED STATES v. HORTON
that point, the State dismissed the state charges, apparently
realizing it was off the hook; it did not have to go through the
effort and uncertainty of trying to prove, to a jury and beyond
a reasonable doubt, that Horton was guilty of the murder.1

   Because the murder is now irrelevant to the Guidelines cal-
culation, the majority’s election to address the sufficiency of
the evidence underlying the cross-reference can be explained
only by the following series of dubious assumptions: (a) the
government will argue on remand that the district court
should disregard the Commission’s instruction to require that
the Harris murder be charged and proven as a separate crime
(or "relevant conduct" in relation to a separate crime); (b) the
district court will foreclose the parties from submitting addi-
tional evidence on whether Horton committed the murder; (c)
the district court will impose an upward variance under 18
U.S.C. § 3553(a) based on a finding that Horton committed
the murder; and (d) a future panel of this court will find the
hypothetical variant sentence substantively reasonable.

   I do not think we should so easily assume the Commission
was so obviously wrong, and I am not convinced the district
court would so assume. Certainly, there is no authority for the
district court to refuse reopening of the evidentiary record
upon the resentencing. And, in any event, nothing this panel
says about the evidence before the district court in the original
sentencing could possibly bind a subsequent panel examining
the evidentiary record created upon the remand for resentenc-
ing. Accordingly, the proper course would be to allow the dis-
trict court to determine in the first instance (and undistracted
by dicta from this court) whether, in its view, reliable evi-
dence of Horton’s alleged involvement in the Harris murder
would justify a substantial upward variance.
  1
   I note that whether Horton was involved in the murder was a close
question on the evidence presented. The government relied entirely on
hearsay, much of which was double- or triple-hearsay, largely from coop-
erators whose veracity could reasonably be questioned on various grounds.
                   UNITED STATES v. HORTON                    33
                               II.

   The majority’s election to reach out and address the eviden-
tiary sufficiency issue also highlights a certain irony. In cases
in which a criminal defendant has appealed a conviction on a
particular count on both sufficiency-of-the-evidence and legal
grounds, and in which there was legal error, this court regu-
larly, and in my view erroneously, declines to decide whether
the evidence was sufficient to support the conviction. See,
e.g., United States v. Lawson, 677 F.3d 629, 651 n.29 (4th
Cir. 2012) (declining to address sufficiency of evidence; new
trial awarded on ground of juror misconduct); United States
v. Golding, 168 F.3d 700, 705 n.* (4th Cir. 1999) (declining
to address sufficiency of evidence; new trial awarded on
ground of prosecutorial misconduct); United States v. King,
650 F.2d 534, 535 n.2 (4th Cir. 1981) (declining to address
sufficiency of evidence; new trial awarded on ground of
denial of right to make closing argument in derogation of
Sixth Amendment); see also United States v. Sandalis, 14 F.
App’x 287, 291 n.7 (4th Cir. Aug. 1, 2001) (unpub.) (suggest-
ing that sufficiency of evidence challenge would be "moot" if
new trial were to be awarded on the basis of juror miscon-
duct), op. after remand, 39 F. App’x 798, 804-05 (4th Cir.
July 3, 2002) (unpub.) (affirming convictions after consider-
ing, inter alia, evidentiary sufficiency).

   That course is improper. Where a defendant shows on
appeal that the evidence was insufficient for the government
to meet its burden of proof, we must remand for the entry of
a judgment of acquittal on the count unsupported by substan-
tial evidence (irrespective of the presence of other legal error)
because subjecting the defendant to a new trial would violate
the Fifth Amendment’s Double Jeopardy Clause. Burks v.
United States, 437 U.S. 1, 11 (1978). In cases where a count
of conviction is tainted by legal error, we cannot fairly (or
logically, I submit), decline to decide a sufficiency challenge
to that count because the disposition of the appeal — remand
for a new trial or remand with instructions to enter a judgment
34                     UNITED STATES v. HORTON
of acquittal—turns on whether the sufficiency challenge is
meritorious.

   Horton’s appeal of his sentence, and other such appeals, are
fundamentally different than appeals of convictions such as
those discussed above, because in this case the Double Jeop-
ardy Clause does not prevent the district court from allowing
the government and/or Horton to present additional evidence
at Horton’s re-sentencing proceeding. "[T]o the extent that the
mandate of the appellate court instructs or permits reconsider-
ation of sentencing issues on remand, the district court may
consider the issue de novo, entertaining any relevant evidence
on that issue that it could have heard at the first hearing."
United States v. Bell, 5 F.3d 64, 67 (4th Cir. 1993) (internal
quotation marks omitted); cf. United States v. Gammage, 580
F.3d 777, 779 (8th Cir. 2009) (remanding for the district court
"to resentence Mr. Gammage based on the record already
before it"). Indeed, the dearth of specific findings by the dis-
trict court at Horton’s initial sentencing hearing prevents us
from discerning whether additional evidence might lead the
court to reconsider its conclusion that the government met its
burden of proof.2

   Therein lies the irony of the majority’s chosen course. On
the one hand, in cases such as Lawson, Golding, and King, we
expressly decline to decide whether a conviction was sup-
ported by substantial evidence, even though deciding that
issue might entitle a defendant to a judgment of acquittal
rather than a bare remand. On the other hand, in cases like this
one, where resolving the sufficiency of the evidence support-
ing a legally erroneous sentencing enhancement is unneces-
sary to the disposition of the appeal—and where a defendant
  2
    The full extent of the district court’s explanation for why it believed
the government had met its burden was this: "I think that the Government
is correct and the probation officer’s got it right," and "The court finds the
basis for the findings contained in the presentence report credible and reli-
able and, therefore, the court adopts those findings." J.A. 791-92.
                       UNITED STATES v. HORTON                            35
might well have new grounds for attacking that evidence upon
resentencing—the majority uses dicta to give the government
a "thumbs up," essentially predicting that the government will
meet its burden again on remand.

   For these reasons, the wise course for us would be to
decline to decide whether the government mustered sufficient
evidence to prove by a preponderance that Horton committed
the August 2007 murder. Sometimes, obiter dicta is both use-
ful and harmless. At other times, it is both useless and harm-
ful, and thus inappropriate. This is one of those cases.

                                    III.

   In response to this concurring opinion, the majority has
inserted its footnote twelve. I confess that I am perplexed by
that footnote.

   It is perfectly clear that the majority has confused Horton’s
legal claim of evidentiary sufficiency, which is the subject
matter of this concurrence, with a claim of "clear error" in the
district court’s factfinding, i.e., a potentially curable factfind-
ing error under the Advisory Sentencing Guidelines.3 Hor-
  3
    Consequently, the majority’s citation to cases in which appellate courts
have remanded cases for resentencing because curable factfinding errors
in the district court’s application of Sentencing Guidelines enhancements
or adjustments were identified, is of no moment in the context of this case.
See, e.g., United States v. Llamas, 599 F.3d 381, 388-90 (4th Cir. 2010)
(guidelines enhancement vacated for inadequate findings), aff’d after
resentencing on remand, ___ F. App’x ___, 2012 WL 1111335, (4th Cir.
April 4, 2012); United States v. Manatau, 647 F.3d 1048, 1056 (10th Cir.
2011) ("On remand, the district court should examine what losses Mr.
Manatau intended.") (emphasis in original); United States v. Flores, 640
F.3d 638, 644-45 (5th Cir. 2011) (sentence vacated where enhancement
was based on district court’s erroneous recitation of trial evidence); United
States v. Newman, 614 F.3d 1232 (11th Cir. 2010).
  Indeed, the last case cited by the majority, United States v. Williams,
527 F.3d 1235 (11th Cir. 2008), seriously cuts against its analysis. In Wil-
36                     UNITED STATES v. HORTON
ton’s brief, at pages 44-50, as an alternative argument to his
principal (and dispositive) argument—the legal impropriety of
the murder cross-reference—unmistakably challenges the suf-

liams, the defendant-appellant was the executive director of a Georgia
non-profit organization receiving federal grant funds. She was convicted
of wire fraud and federal funds theft for redirecting a portion of those
grant funds to unauthorized uses. On appeal, she challenged three guide-
lines adjustments: (1) aggravated-role; (2) abuse-of-trust; and (3) obstruc-
tion of justice. The Eleventh Circuit sustained application of the latter
adjustment but found legal error in the district court’s application of the
first two adjustments. In other words, in holding that at the resentencing
after the remand the district court was flatly prohibited from reconsidering
the first two adjustments, the Eleventh Circuit relied on the limited factual
record before it, coupled with its legal determination, e.g., whether the
husband could be deemed a participant in the scheme and whether appel-
lant occupied a position of trust in respect to the federal grantor. See id.
at 1249 ("Because the evidence is insufficient as a matter of law to show
that Williams was ‘an organizer, leader, manager, or supervisor of one or
more other participants in criminal activity,’ we conclude that the district
court erred in applying the two-level aggravated-role adjustment under
U.S.S.G. § 3B1.1(c)." (emphasis added)); id. at 1251-52 ("Because there
is no evidence that CNCS entrusted Williams with discretionary authority
or placed a special trust, akin to that of a fiduciary, in Williams, the dis-
trict court erred in applying the abuse-of-trust adjustment based on Wil-
liams’s relationship with CNCS. On remand, the district court shall re-
calculate Williams’s advisory Guidelines sentence without the § 3B1.3
adjustment." (emphasis added)); id. at 1252 ("As to Williams’s sentence,
the district court’s factual findings do not justify application of adjust-
ments for aggravated role or for abuse of trust. Therefore, we vacate Wil-
liams’s sentence and remand for resentencing without the upward
adjustments under U.S.S.G. §§ 3B1.1(c) and 3B1.3." (emphasis added)).
   Thus, in Williams, the appellate court’s assessment of the factual record,
in light of the controlling legal standards, prompted the court to find insuf-
ficient evidence to support two of the adjustments sought by the govern-
ment and to mandate that those two adjustments were inapplicable as a
matter of law; the court appropriately instructed the district court to
impose a sentence upon remand without regard to those adjustments. The
court did not, as the majority does here, go out of its way to signal the dis-
trict court that it could resort to 18 U.S.C. § 3553(a) to achieve the same
sentence of incarceration that had been imposed as a result of legal error
in the calculation of the appellant’s Guidelines sentencing range.
                      UNITED STATES v. HORTON                          37
ficiency of the evidence that he was involved in the Harris
murder. See Appellant’s Brief at 44, Argument Heading ("A
PREPONDERANCE OF THE EVIDENCE DID NOT SUP-
PORT THE CROSS-REFERENCE TO FIRST DEGREE
MURDER"). It is Horton, not the majority, that has presented
his issues "in their logical order." Because our resolution of
the dispositive legal issue of the murder cross-reference fully
disposes of the sentencing claim as the case comes to us, we
should stop there.

   The majority’s response to this simple truth, see ante n.12
("If we had concluded that the district court clearly erred in
its factual determination regarding the August 17, 2007 mur-
der, the more complicated issue of the murder cross-
reference’s applicability would not have been reached.") is
absolutely baffling. When a "more complicated" issue is a
legal issue crying out for resolution for the benefit of the dis-
trict judges in this circuit and the lawyers appearing before
them, it would have been a derogation of our responsibility to
clarify the law for this panel to have attempted to duck that
issue, no matter how "complicated."4 And, I unhesitatingly
note, the majority opinion performs that job with exquisite
cogency and clarity.

   Finally, the majority’s reliance on dicta from United States
v. Susi, 674 F.3d 278 (4th Cir. 2012), is unavailing. I do not
doubt that in any case this court’s mandate may expressly
authorize, see, e.g., Bell, 5 F.3d at 67, or it may expressly pro-
hibit, see, e.g., Gammage, 580 F.3d at 779, a district court’s
reopening of the factual record upon a remand for resentenc-
ing. It is the mandate that is the sole authority for such cabin-
ing of a district court’s authority. In any event, as Susi made
  4
    As the docket of this case shows, acting nostra sponte barely three
weeks before oral argument, we ordered counsel to file supplemental
briefs on the guideline cross-reference issue. This action was entirely in
keeping with the high importance of that issue, which is nicely resolved
in the majority opinion.
38                   UNITED STATES v. HORTON
perfectly clear, that case was decided on the basis of harmless
error, not the absence of error; thus, it has no salience here.
See Susi, 674 F.3d at 283 ("We need not resolve whether the
district court erred in concluding that it was barred from
reconsidering the Sentencing Guidelines calculation, because
even if we assume that the district court erred in this respect,
that error was harmless under the facts of this case.").

                              ***

     In sum, we should say no more than is needed in this case.
