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SJC-11630
SJC-11631

                  COMMONWEALTH vs. MICHAEL COWELS.
                   COMMONWEALTH vs. MICHAEL MIMS.



       Suffolk.       October 9, 2014. - February 12, 2015.

 Present:   Gants, C.J., Spina, Cordy, Botsford, Duffly, Lenk, &
                            Hines, JJ.

Homicide. Deoxyribonucleic Acid. Evidence, Credibility of
     witness. Witness, Credibility. Practice, Criminal,
     Capital case, New trial.



     Indictments found and returned in the Superior Court
Department on August 6, 1993.

     Following review by this court, 425 Mass. 279 (1997),
motions for a new trial, filed on February 4 and March 24, 2008,
were considered by Thomas E. Connolly, J.

     Requests for leave to appeal were allowed by Cordy, J., in
the Supreme Judicial Court for the county of Suffolk.


     David J. Apfel (Nicholas K. Mitrokostas & Joshua M. Daniels
with him) for Michael Cowels.
     Philip G. Cormier for Michael Mims.
     Helle Sachse, Assistant District Attorney (Janis DiLoreto
Noble, Assistant District Attorney, with her) for the
Commonwealth.
                                                                      2


    LENK, J.    The defendants, Michael Cowels and Michael Mims,

were convicted by a Superior Court jury in December, 1994, of

murder in the first degree in the stabbing death of Belinda

Miscioscia.    Among the evidence presented against them at trial

were two "bloody" towels.     The Commonwealth offered testimony

suggesting that the defendants had used the towels to clean

themselves after stabbing the victim.     Testing performed on the

towels at the time of the trial indicated the presence of human

blood.   The testing, however, was inconclusive.    Further testing

was performed on just one of the towels; the sample on the other

was too small to be tested.     An expert testified that the

further testing neither identified nor excluded the defendants

or the victim as the sources of the blood.     In June, 1997, this

court affirmed the defendants' convictions.     See Commonwealth v.

Cowels, 425 Mass. 279, 285-293 (1997).

    In 2008, the defendants filed separate motions for a new

trial, based in part on deoxyribonucleic acid (DNA) testing

performed on the previously tested towel by an independent

laboratory after their convictions.     That testing revealed that

the blood contained on the towel did not belong to either of the

defendants or the victim, but instead to an unidentified male.

The defendants also argued in their motions that they had been

deprived of the effective assistance of counsel.
                                                                    3


    After a nonevidentiary hearing, the motion judge, who was

also the trial judge, denied the motions.    In 2011, each

defendant filed a "gatekeeper" petition before a single justice

of the county court, pursuant to G. L. c. 278, § 33E, seeking

leave to appeal from the denial of his motion for a new trial.

In January, 2014, the single justice allowed both petitions, and

the matters were entered in this court the following month.

    We conclude that, given the towels' role as one of the few

pieces of physical evidence that corroborated the testimony of a

key prosecution witness whose credibility was sharply

challenged, the towels likely were a real factor in the jury's

deliberations.   Consequently, we believe that there is a

substantial risk that, had the newly available DNA testing been

available at the time of the trial and resulted in the

inadmissibility of the towels in the Commonwealth's case, the

outcome of the trial would have been different.    The defendants,

therefore, must receive a new trial.

    1.   Background.   a.   Evidence at trial.   Misciosia's body

was found in a yard behind an industrial building in Chelsea on

the morning of Monday, June 28, 1993.    An autopsy revealed that

she had been stabbed six times.   The fatal stab wound perforated

her heart.   She also had been slashed several times, and

suffered numerous bruises and defensive wounds.    Her body and

clothing were "blood soaked."   A pair of eyeglasses was found a
                                                                   4


few feet from the body, and a bag of marijuana was stuffed

inside of her bra.

    The police investigation quickly turned towards the

defendants, as they were among the last people to have seen the

victim alive on the preceding Saturday night.    The trial

presented the jury with two conflicting timelines of the

defendants' activities on that night.

    The Commonwealth presented -- largely through the testimony

of Robert Salie, a friend of Cowels and Mims -- the following

timeline.    On the night of Saturday, June 26, 1993, the victim

was in her brother's apartment in Chelsea with her brother, her

brother's girl friend, and Peter Rowe, whom the victim was

dating.   The victim and Rowe had plans to go to the Wonderland

Ballroom that evening.    According to the witnesses present in

the apartment, the victim left by herself shortly before 9 P.M.

to purchase marijuana for the group from Cowels.    She had come

to know Cowels while attending a course that she was required to

take in conjunction with a conviction of operating a motor

vehicle while under the influence of alcohol.

    The victim met Cowels a few blocks away from the apartment,

where Cowels was attending a party along with his friend, Mims.

After purchasing the marijuana, the victim did not return to the

apartment.   Instead, Salie testified, Cowels, Mims, and the

victim arrived at Salie's home, located approximately one and
                                                                      5


one-half miles from the location of the party, at approximately

9:30 P.M.    There the four smoked a marijuana cigarette, and

Salie witnessed the victim and the defendants prepare to have

sex in his bedroom.     Salie was invited to participate, but

declined.    The defendants and the victim then emerged from

Salie's bedroom and left his apartment shortly afterwards.

    Salie testified that the defendants returned to his

apartment, unaccompanied by the victim, at approximately

11:30 P.M.    After he allowed them to enter, they immediately

went to his bathroom.     They remained in the bathroom for

approximately twenty minutes, during which time he could hear

the water running in the sink.     When the defendants emerged from

the bathroom, Cowels was in his underwear and carrying a plastic

bag containing the clothes he had been wearing that evening.

Heading towards Salie's bedroom, Cowels asked Salie if he could

borrow some clothes.     Cowels also held out a sneaker that he had

been wearing, on which Salie saw a spot that he believed to be

blood.   "[I]f you fuck with me," Cowels told Salie, "this is

what happens."    Cowels remarked that Salie would read in the

newspapers the following day about "[h]ow we killed her,"

adding, "she was a fucking pig and she got what she deserved."

He told Salie that "if [he] said anything [he]'d get hurt."

    Salie gave clothes to both defendants.      After dressing,

Mims told Salie to "keep [his] mouth shut," and Cowels put a
                                                                    6


finger to Salie's head and reiterated that if Salie said

anything, he would "get fucking hurt."    The defendants left

carrying bags of their clothing.

    The defendants returned at approximately 1 A.M., without

their bags, and again told Salie that he had "better keep [his]

mouth shut."   Cowels departed, while Mims spent the night on a

couch in Salie's apartment.   On his way out, Cowels gave Salie a

ride to the store to purchase a pack of cigarettes.

    Although Salie's testimony was crucial to the

Commonwealth's case, his credibility was extensively impeached

during cross-examination.   In his first two interviews with

police, Salie had not offered the account that he ultimately

offered at trial.   Instead, he indicated that the defendants had

come to his apartment only once on the evening of the victim's

death, when Mims arrived to sleep over, and that the victim was

never present in his apartment.    Salie offered the narrative to

which he later testified at trial after he learned that he could

be charged as an accessory after the fact for providing the

defendants with clothing.   Salie also entered into a cooperation

agreement with the Commonwealth under which he avoided a

mandatory term of incarceration for several unrelated motor

vehicle offenses, for which Cowels had been called to serve as a

prosecution witness against Salie.   Salie had a long criminal

history, including numerous drug-related offenses, and admitted
                                                                       7


to being a recovering heroin addict.    Finally, the defense

challenged the inconsistency between Salie's testimony that he

was afraid of the defendants and his decision to go for a ride

with Cowels to pick up cigarettes immediately after Cowels

supposedly threatened him, and to watch a softball game in which

the defendants were playing on the following day.

    The Commonwealth offered evidence that, it contended,

corroborated Salie's testimony.   Approximately one month after

the stabbing, police recovered two towels, one from inside and

the other from behind a hamper in Salie's bathroom.       The towels

were visibly stained; one was a large bath towel containing a

large, rust-colored stain, covering the majority of the towel's

surface.   Testing confirmed the presence of human blood on both.

Salie testified that he last saw the towels on June 26, 1993,

when they were on the rack in his bathroom and were clean.

According to the Commonwealth's serologist, the bloodstains on

one towel -- a small hand towel -- were too small to be tested

without exhausting the sample.    Further testing performed on the

other towel revealed a "weak reaction" to type A blood.       Both of

the defendants and the victim have type O blood.    The

Commonwealth's serologist, however, testified that the reaction

was too weak to draw any conclusions from it, stating that the

blood on the towel could belong to anybody.
                                                                     8


    The Commonwealth also introduced evidence that both of the

defendants got rid of their old shoes and acquired new ones at

approximately the same time shortly after the murder.     An

officer who interviewed Cowels soon after the stabbing testified

that he appeared at the police station wearing "a brand new pair

of white high-top sneakers."   Richard Polovick, a friend of

Cowels, testified that, sometime after the victim's death,

Cowels stopped and asked Polovick to repair a tire on his Chevy

Nova automobile.   When Cowels opened the trunk of the vehicle,

Polovick saw a pair of sneakers.   Polovick asked Cowels whether

the shoes were the "notorious sneakers that people were talking

about."   Cowels responded, "Yes, that's them," and Polovick

watched as Cowels threw the sneakers into some bushes.    Polovick

later directed police to the location, where the sneakers were

recovered several weeks after they had been left.   Testing

revealed trace amounts of nonvisible, "occult" blood in a

recessed portion of the sole of one of the sneakers.     The

forensic examiner, however, testified that the sample was too

small to determine the blood type, or even whether it came from

a human or an animal.

    Similarly, the Commonwealth offered testimony that Mims

appeared to play softball with friends on Sunday, June 27,

wearing "green high-tech[] sneakers," which Salie testified he

had lent to Mims the previous night.   Asked by a friend what had
                                                                    9


happened to his old sneakers, which were expensive Reebok high-

tops that were in good condition the last time the friend saw

them, Mims responded that he had thrown them out because they

had gotten "wet and squeaky" in the rain the previous night.

However, it had not rained that night.     Unlike Cowels's shoes,

Mims's shoes were never recovered.

    Finally, the prosecution offered evidence of a vaginal

smear swab taken from the victim.    Testing of the swab revealed

the presence of semen.     The Commonwealth's expert, however,

testified that she could not identify, based on her analysis of

the swab, whether the seminal fluid came from either of the

defendants or both, or from someone else altogether.

    In addition to the evidence that was introduced to

corroborate Salie's account of the evening, the Commonwealth

offered evidence that the defendants sought to construct a false

alibi in the days following the murder.     Larry Bavis testified

that the defendants and a third person named Victor Grimaldi

urged Bavis to lie to "cover" for them by saying that he was

playing pool with them at Triple O's, a bar in the South Boston

section of Boston, on the night of the stabbing.     In response to

that request, Bavis became angry, and called the police to

report the conversation.

    Additionally, a police officer who interviewed Cowels

shortly after the victim's death testified to several
                                                                     10


incriminating statements Cowels made.     Cowels indicated that he

had met the victim at "drunk driving school," and that he had

had sex with her on several previous occasions, although he had

not done so for "several months."   According to the officer's

testimony, Cowels described the victim as a "dirty pig," and

said that she was "such a dirty pig that one time he and Mims

had had sex with her at the same time."    When the officer

informed Cowels that the victim was dead, Cowels "began

sobbing," and stated, "I'm only twenty-three.     I don't want to

go to jail."

    The defendants offered an alternative timeline of their

activities that evening, which was introduced at trial primarily

through the same police officer's account of what the defendants

had said to him during an interview.    According to this

timeline, the victim arrived at the party in Chelsea to purchase

marijuana at approximately 7:30 P.M., rather than 9 P.M. as in

the Commonwealth's version.   The defendants, the victim, and

Grimaldi then traveled to Triple O's, where they played pool and

drank until approximately 11 P.M.   At 11 P.M they left;

Grimaldi, who lived upstairs from Triple O's, went home;

meanwhile, the victim accompanied the defendants to the

residence in Revere that Cowels shared with his sister, Barbara

Cowels.   About twenty minutes later, Barbara Cowels arrived at

her home, where she encountered the defendants and the victim.
                                                                    11


She chastised her brother for drinking, and kicked him out of

the house.   The defendants then dropped the victim off near the

party where they had picked her up at the beginning of the

evening, and continued on to a bar in Revere, where they

remained until approximately 2 A.M.     Once the bar closed, the

defendants went to Salie's house, purportedly for the first time

that evening.   Mims spent the night there, while Cowels went to

his girl friend's house.

    The defense introduced testimony by four witnesses.         Two of

those witnesses corroborated this alternative timeline.    Barbara

Cowels testified that when she arrived at her home at

approximately 11:20 P.M. that Saturday night, she encountered

the defendants along with the victim.     She stated that, after a

brief argument with Cowels concerning his drinking, the

defendants and the victim left the house.     Similarly, John

Heald, a friend and neighbor of the Cowelses, testified that on

the evening of the stabbing, sometime between 10 and 11:30 P.M.,

he observed the defendants leaving the apartment with a young

woman.   Because the testimony of both of these witnesses in

conjunction suggested that the victim was still alive and in the

company of the defendants at approximately 11:30 P.M., it
                                                                   12


undermined Salie's statement that the defendants arrived at his

apartment to clean up after the stabbing at that time.1

     The defense also introduced an alternative account of the

incident when Cowels asked Polovick to repair a tire.     A

coworker at the print shop where Cowels was employed at the time

of the stabbing testified that he accompanied Cowels on a trip

to purchase new sneakers.   On the way, he and Cowels stopped to

have Polovick repair a tire.    According to the coworker's

testimony, after Polovick repaired the tire, he and Cowels

continued on to a shoe store.   There Cowels purchased new

sneakers and put the old sneakers on the back seat of his

vehicle.   The coworker also testified that workers at the print

shop got ink and chemicals all over any clothes that they wore

to work, and that Cowels wore his sneakers to work.

     Finally, the defense called a chemist at the State police

crime laboratory.   The chemist, who was not assigned to the

     1
       On appeal, the Commonwealth describes Barbara Cowels's
testimony as if it were consistent with the timeline of events
that the prosecution presented at trial. Robert Salie, however,
testified that the defendants arrived at his apartment to clean
up at 11:30 P.M. Meanwhile, Barbara Cowels testified that she
arrived home at 11:20 P.M., and ordered the defendants and the
victim out of the house approximately five to ten minutes later,
leaving the defendants at most five minutes to travel to the
industrial park in Chelsea where the victim's body ultimately
was found, kill the victim, and then travel to Salie's apartment
to clean up. To believe that Barbara Cowels's testimony was
accurate, therefore, the jury would have had to conclude that
Salie's testimony was inaccurate, at least with respect to the
time when the defendants arrived at his apartment for the second
time that evening.
                                                                    13


case, testified that she believed that the laboratory could have

performed a comparison test, using blood from the victim and the

defendants, that could have determined whether any of them was

the source of the blood found on the towel.     No comparison test,

however, was ever performed.    Both defendants were found guilty

of murder in the first degree on a theory of extreme atrocity or

cruelty.

    b.     Posttrial proceedings.   After this court affirmed the

defendants' convictions, Commonwealth v. Cowels, 425 Mass. 279,

285-293 (1997), Mims filed a petition for a writ of habeas

corpus in the United States District Court for the District of

Massachusetts.   Mims vs. DiPaolo, 98-CV-11203-MEL (D. Mass.

Apr. 1, 1999).   The petition was denied, and, in an unpublished

opinion, the United States Court of Appeals for the First

Circuit affirmed the denial.    Mims v. DiPaolo, 201 F.3d 428 (1st

Cir. 2000).

    Cowels, initially proceeding pro se, moved for a new trial

on July 3, 1998.   Cowels later filed an assented-to motion to

stay proceedings on his motion for a new trial while his

subsequently obtained counsel sought permission to perform DNA

testing on certain items of evidence.     A Superior Court judge,

who was also the trial judge, authorized Orchid Cellmark

(Cellmark) to perform the requested testing.     DNA testing on the

towel that had been subjected to further testing in the original
                                                                    14


trial revealed that the blood found on it did not come from

either of the defendants or the victim, but instead from an

unidentified male.     DNA testing of the vaginal swab taken from

the victim identified Mims as a contributor of sperm recovered

from the victim, and excluded Cowels as a contributor.        Cellmark

also replicated the presumptive test for blood which the

Commonwealth had performed on the sneakers before the first

trial.    Cellmark's test established that there was no blood on

the parts of the sneakers that were tested.

    Based on the results of these tests, in February, 2008,

Cowels filed an amended motion for a new trial.     Shortly

thereafter, Mims also sought a new trial, pressing the same

arguments as Cowels.    The defendants argued that they were

entitled to a new trial based on "newly discovered" evidence, in

the form of the DNA test results on the towel and the vaginal

swab.     They further contended that they were deprived of

effective assistance of counsel because trial counsel (1) failed

to conduct independent forensic testing on the sneakers;

(2) failed to call certain witnesses whose testimony would have

corroborated the defendants' account of their activities that

evening; and (3) failed adequately to develop the defense that

Peter Rowe, who had been dating the victim and had been "stood

up" by the victim on the night of the stabbing, was the actual

killer.
                                                                    15


    The judge2 rejected both arguments and denied the

defendants' motions for a new trial.    The judge concluded that

the towels would not have been admissible in light of the DNA

testing establishing that neither the defendants nor the victim

were the source of the blood found on one of the towels.     The

judge determined, however, that "there is no substantial risk

that the jury would have reached a different conclusion if the

'bloody' towels were not in evidence."    The judge also rejected

the ineffective assistance of counsel arguments.

    2.    Discussion.    The defendants argue, as they did in their

original motions, that they are entitled to a new trial based on

(1) newly discovered evidence, in the form of the DNA testing on

one of the towels and the vaginal swab; and (2) ineffective

assistance of counsel.    In reviewing a judge's decision on a

motion for a new trial, we "examine the motion judge's

conclusion only to determine whether there has been a

significant error of law or other abuse of discretion."

Commonwealth v. Grace, 397 Mass. 303, 307 (1986).    While we

"extend[] special deference to the action of a motion judge

who[, as here,] was also the trial judge," id., we nonetheless

conclude that, in the circumstances here, the defendants are

entitled to a new trial based on the DNA testing performed on



    2
        The judge has since retired.
                                                                16


the towel.3   Accordingly, we need not reach the defendants'

claims based on the vaginal swab testing or their ineffective

assistance of counsel claims.4


     3
       The judge denied the defendants' motions for a new trial
without conducting an evidentiary hearing. The Commonwealth
contends that, as a result, we "should only decide whether the
defendant[s are] entitled to an evidentiary hearing, and not
whether [they are] entitled to a new trial." We of course may
remand a motion for a new trial to the Superior Court with
instructions regarding the conduct of an evidentiary hearing.
See Commonwealth v. DiBenedetto, 458 Mass. 657, 670-671 (2011).
The Commonwealth identifies no case, however, holding that,
where a judge of the Superior Court denies a motion for a new
trial without holding an evidentiary hearing, our review is
limited to the decision not to hold the evidentiary hearing and
does not reach the underlying denial of the motion.

     Typically, "where a substantial issue is raised [on a
motion for a new trial] and is supported by a substantial
evidentiary showing, the judge should hold an evidentiary
hearing" before granting the motion. Commonwealth v. Gordon, 82
Mass. App. Ct. 389, 394-395 (2012), quoting Commonwealth v.
Stewart, 383 Mass. 253, 260 (1981). Here, however, we have
determined that the only issue warranting an evidentiary
hearing -- the Commonwealth's recent contention that the
deoxyribonucleic acid (DNA) testing does not constitute "newly
discovered" evidence -- was waived below, and cannot be raised
on appeal. Remand for an evidentiary hearing, therefore, is not
warranted.
     4
       The defendants argue that "the new DNA evidence pertaining
to the vaginal swab would also probably have been a real factor
in the jury's deliberations, at least against Cowels." The
defendants argue that the swab test corroborates Cowels's
account of the evening, insofar as it establishes that he did
not have sex with the victim, undercuts Salie's credibility, and
undermines the Commonwealth's theory that the defendants killed
the victim because they regarded her as a sexual object. The
Commonwealth counters that Salie never testified that he
actually witnessed the defendants engaging in sexual intercourse
and that the newly discovered evidence is broadly consistent
with Cowels's statement to police that the victim had had some
sexual contact with both defendants on the evening of the
                                                                   17


    Rule 30 (b) of the Massachusetts Rules of Criminal

Procedure, as appearing in 435 Mass. 1501 (2001), allows a trial

judge to "grant a new trial at any time if it appears that

justice may not have been done."   To prevail on a motion for a

new trial on the basis of newly discovered evidence, a defendant

must meet both prongs of a two-part test.   First, a defendant

"must establish that the evidence was unknown to the defendant

or trial counsel and not reasonably discoverable at the time of

trial."   Commonwealth v. Shuman, 445 Mass. 268, 271 (2005).

Second, a defendant must show that the evidence "casts real

doubt on the justice of the conviction."    Commonwealth v. Grace,

397 Mass. at 305.   The Commonwealth contends that the defendants

have failed to satisfy either of the elements necessary to

prevail on a motion for a new trial.

    a.    In its brief, the Commonwealth maintains that the DNA

evidence identified on the towels recovered from Salie's

bathroom does not constitute "newly discovered" evidence.      Even

if the argument were not waived, we would find it unpersuasive,

given that this court did not determine the admissibility of DNA

testing of the type performed here until 1997, Commonwealth v.



murder, but had had more with Mims. Because we conclude that
the towels likely were a real factor in the jury's
deliberations, we need not reach the question whether the
vaginal smear swab -- taken by itself -- would have been
sufficient to give rise to a substantial risk that the outcome
of the trial would have been different.
                                                                    18


Vao Sok, 425 Mass. 787, 789 (1997), and that the very article

that the Commonwealth cites as establishing that DNA testing was

available in 1993 indicates that it was then "still at the

experimental stage."   Thompson, Evaluating the Admissibility of

New Genetic Identification Tests:    Lessons from the "DNA War,"

84 J. Crim. L. & Criminology 22, 30 n.36 (1993).   We need not

reach the issue of whether the evidence is "newly discovered,"

however, since it plainly was waived.    Generally, "[a]n issue

not raised or argued below may not be argued for the first time

on appeal."    Carey v. New England Organ Bank, 446 Mass. 270, 285

(2006), quoting Century Fire & Marine Ins. Corp. v. Bank of New

England–Bristol County, N.A., 405 Mass. 420, 421 n.2 (1989).

See Commonwealth v. LaBriola, 430 Mass 569, 570 n.1 (2000).       As

the judge observed, in the proceedings below "[t]he Commonwealth

d[id] not dispute that the DNA results are 'newly discovered.'"

    b.   To satisfy the second element of the test for a motion

for a new trial, a defendant must establish that the new

evidence is:

    "not only . . . material and credible[,] but also [that
    it] . . . carr[ies] a measure of strength in support of the
    defendant's position. . . . Thus newly discovered evidence
    that is cumulative of evidence admitted at the trial tends
    to carry less weight than new evidence that is different in
    kind. . . . Moreover, the judge must find there is a
    substantial risk that the jury would have reached a
    different conclusion had the evidence been admitted at
    trial. . . . The strength of the case against a criminal
    defendant, therefore, may weaken the effect of evidence
    which is admittedly newly discovered. . . . The motion
                                                                  19


    judge decides not whether the verdict would have been
    different, but rather whether the new evidence would
    probably have been a real factor in the jury's
    deliberations." (Citations omitted).

Commonwealth v. Grace, 397 Mass. at 306.

    This case differs from many cases involving motions for a

new trial on the basis of newly discovered evidence in one

respect.   In such cases, a defendant generally offers newly

discovered evidence that was not presented in the original

trial, but that, the defendant argues, probably would have been

a real factor in the jury's deliberations if it had been

offered.   See, e.g., Commonwealth v. Wright, 469 Mass. 447, 447-

448 (2014) (defendant argued "that newly discovered evidence in

the form of third-party culprit evidence warranted a new

trial"); Commonwealth v. Raymond, 450 Mass. 729, 729-730 (2008)

("The defendant alleges that the prosecution withheld the fact

of an agreement it purportedly made with a key witness . . .").

The defendants' motions here, however, are based less on newly

discovered evidence that could have been admitted in evidence at

the trial, than on newly available analysis that would remove

from the jury's consideration evidence admitted at trial in the

Commonwealth's case.   The judge observed that "the 'bloody'

towels would not have been admitted in evidence had DNA testing

shown that the blood on the towels was not that of Cowels, Mims,

or Miscioscia."   Although the defendants suggest that they might
                                                                  20


offer the DNA testing performed on one of the towels in evidence

in a new trial, ostensibly to support an argument that Salie

intentionally "frame[d]" the defendants, the primary value of

the DNA testing for the defendants plainly derives from the way

in which it eliminates the towels as evidence against the

defendants.

    This distinction, however, does not raise significant

conceptual problems for our analysis.   In the typical case,

where a defendant argues on the basis of newly discovered

exculpatory evidence that was not presented at the original

trial, we ask "whether the new evidence would probably have been

a real factor in the jury's deliberations" had it been presented

(emphasis supplied).   Commonwealth v. Grace, 397 Mass. at 306.

In this case, where the defendants argue on the basis of a newly

available analysis that likely would have rendered inculpatory

evidence presented at the original trial inadmissible, we ask

whether that inculpatory evidence "likely was a 'real factor' in

the jury's deliberations such that its elimination would cast

real doubt on the justice of the defendant's conviction"

(emphasis supplied).   Commonwealth v. Sullivan, 469 Mass. 340,

350 (2014).   See Commonwealth v. DiBenedetto, 458 Mass. 657, 667

(2011), quoting Commonwealth v. Grace, supra (in case where

newly available analysis undermines test results presented in

initial trial, analyzing whether "evidence concerning the . . .
                                                                    21


test results probably was not 'a real factor in the jury's

deliberations,' and not likely to create 'a substantial risk

that the jury would have reached a different conclusion' if it

had not been admitted at trial").   If we conclude that the

subsequently eliminated inculpatory evidence likely did play an

important role in the jury's deliberations, then we must

conclude that there is a "'a substantial risk that the jury

would have reached a different conclusion' if it had not been

admitted at trial."

    After a detailed review of the trial record, we determine

that the towels likely were a "real factor" in the jury's

deliberations, and that there is consequently a substantial risk

that the outcome of the trial would have been different had the

towels been excluded altogether or neutralized through expert

testimony indicating that blood found on one of the towels

matched neither the defendants nor the victim.   We reach this

conclusion based on the paucity of physical evidence in the

case, the vital importance of Salie's testimony, and the

substantial challenges to his credibility.

    The case against the defendants was entirely

circumstantial.   There were no eyewitnesses to the crime.    The

Commonwealth never found the murder weapon.   There was no

forensic evidence at the crime scene tying either defendant to

the crime.   Although the victim's body showed defensive wounds,
                                                                    22


a police investigator who interviewed Cowels and Mims within

days of the stabbing observed no cuts or scratches on either

defendant.    The only physical evidence that the Commonwealth

offered linking the defendants to the crime was the towels,

Cowels's sneaker, and the vaginal swab.

    Due to the dearth of physical evidence, the case against

the defendants hinged, to a significant extent, on the testimony

of Salie.    The problems with Salie's credibility, moreover, were

numerous and significant.    In the prosecutor's own words, Salie

was "a junkie" with a "checkered background" and a "long

criminal record."    Indeed, he was impeached at trial with at

least nineteen prior convictions of crimes ranging from drug

possession to arson.    Salie originally had given an account that

was consistent with Cowels's and Mims's claim that they only

visited his home once on that evening, before changing his

account to the narrative presented at trial.    Salie, moreover,

had a motive to change his story, and to point his finger at

Cowels specifically:    not only did Salie's testimony enable him

to avoid prosecution as an accessory after the fact, but it also

allowed him to avoid jail time on an unrelated motor vehicle

offense, for which Cowels was to serve as a witness for the

prosecution.    It is, in short, difficult to imagine a witness

with more credibility problems than Salie.
                                                                      23


    To counter these issues with Salie's credibility, the

prosecutor repeatedly emphasized the ways in which Salie's

testimony had been "confirmed" and "verified."      He observed that

Salie's testimony had been "validated by so many different

people and so many different sources."     The prosecutor referred

to the towels in the context of this discussion, as evidence

that "substantiated" Salie's account.      Noting Salie's testimony

that the defendants ran into his bathroom to clean and change,

the prosecutor stated:   "And when the police do a search, what

do they find?   They find bloody towels.    Those towels are in

evidence, ladies and gentlemen.   Another piece confirming Mr.

Salie."

    This court has observed that evidence likely functions as a

real factor in a jury's deliberations where the evidence "is

more credible than any other evidence on the same factual issue

and bears directly on a crucial issue before the jury, such as

the credibility of an important prosecution witness."

Commonwealth v. Tucceri, 412 Mass. 401, 414 (1992).      Here, the

towels were the only physical evidence corroborating a key

element of an important prosecution witness's testimony, and

functioned to reinforce Salie's severely challenged credibility.

Accordingly, we conclude that the towels likely were a real

factor in the jury's deliberations.
                                                                  24


    The Superior Court judge offered several reasons for

reaching the contrary conclusion.   First, the judge observed

that the Commonwealth's expert testified that the testing

performed on the towels was "inconclusive," and that defense

counsel's closing arguments "highlight[ed] the limited

evidentiary value of the 'bloody' towels."   The Commonwealth

echoes that argument on appeal.   It contends that, because the

testing performed on the towels was inconclusive, "[r]emoving

the towel [tested by Cellmark] from the calculus of the trial,

or adding to it the fact that neither defendant['s] nor the

victim's blood was found on the towel, . . . does not 'carry a

measure of strength in support of the defendant's position.'"

    There is, however, a significant difference between a test

that fails to say whether the blood came from the defendants or

the victim and a test that definitively establishes that the

blood did not come from either the defendants or the victim.

The inconclusive test results allowed the prosecutor to cite the

"bloody towels" as physical evidence that corroborated Salie's

testimony.   As the defendants argue, "the use of the towel at

trial was a . . . powerful visual for the jury."   A test that

definitively excluded the defendants and the victim, by

contrast, would not merely have reduced the weight that the jury

might have given the towels in substantiating Salie's testimony.
                                                                  25


Rather, it would have meant that the towels would not have been

admissible at all, at least when offered by the prosecution.

    Second, the judge concluded that, although the towels

functioned to corroborate Salie's testimony, they likely were

not a real factor in the jury's deliberations because "Salie's

credibility was brought into question numerous times throughout

his testimony," and there were "numerous reasons put forth at

trial for finding Salie's testimony unreliable and incredible."

But the repeated challenges to Salie's credibility increase,

rather than decrease, the importance that the towels likely had

in the jury's deliberations.    It is difficult to see how the

jury could have voted to convict if the jurors had not believed

Salie's testimony.    Much of the other evidence against the

defendants was valuable primarily because it confirmed details

in Salie's account:    the original testing of the vaginal swab

smear confirmed Salie's statement that he witnessed the

defendants and the victim preparing to have sex; Polovick's

testimony regarding Cowels's disposal of his sneaker and the

original testing performed on the shoe were valuable because

they confirmed Salie's testimony that Cowels brandished a bloody

sneaker at him after the murder.    Furthermore, Salie's testimony

that the defendants came into his apartment, cleaned up, and

discarded their clothing on the evening of the killing explained

why the prosecution could not present any other physical
                                                                  26


evidence linking the defendants with an especially bloody

stabbing.   Because the jury's verdict indicates that the jury

very likely did credit Salie's testimony, despite the challenges

it faced, and because the towels were among the very few pieces

of physical evidence that buttressed Salie's credibility, there

is a real question whether the jury would have credited his

testimony had the towels not been presented.

    Third, the judge cited case law holding that "evidence of a

type merely tending to impeach or to corroborate credibility of

a witness ordinarily will not be the basis for ordering a new

trial."   Commonwealth v. Shuman, 17 Mass. App. Ct. 441, 448

(1984), overruled in part on other grounds by Commonwealth v.

Jones, 59 Mass. App. Ct. 157 (2003).   However, we have never

adopted an inflexible rule that newly discovered evidence that

merely corroborates or impeaches a witness's testimony is an

insufficient basis for a motion for a new trial.   In fact, we

have found that, in rare cases, a new trial may be warranted

"[w]here the Commonwealth's case depends so heavily on the

testimony of a witness" and where the newly discovered evidence

"seriously undermines the credibility of that witness."

Commonwealth v. Liebman, 388 Mass. 483, 489 (1983).

Furthermore, the DNA testing on the towel does not "merely

impeach" Salie's testimony.   Commonwealth v. Sullivan, 469 Mass.

340, 352 (2014).   Rather, it "negates a key piece of physical
                                                                     27


evidence that the prosecution relied on in arguing that the jury

should credit [Salie's] testimony."     Id.   In Commonwealth v.

Sullivan, supra at 353, we affirmed a Superior Court judge's

decision granting a defendant's motion for a new trial based on

newly discovered evidence.    There, in the original murder trial,

the Commonwealth had offered expert testimony indicating that a

jacket, allegedly worn by the defendant during the commission of

the crime, had blood on its cuffs that was "'consistent' with

that of the victim."   Id. at 345.    There, as here, the

prosecutor argued in closing that the jacket corroborated the

testimony of a witness whose credibility was significantly

challenged.   Id. at 349.    There, as here, subsequent DNA testing

excluded the victim as the source for the genetic material

identified on the jacket.     Id. at 349-350.   We concluded that

"the purported blood on the defendant's cuffs and the hair in

[the] defendant's pocket were not merely cumulative of other

physical evidence presented at trial."     Id. at 352.     Rather,

"[t]hey were different in kind because they served as the sole

pieces of physical evidence indicating the defendant had been in

the presence of the victim during the killing."      Id.

    Here, similarly, Salie testified that the defendants spent

twenty minutes in his bathroom cleaning up after allegedly

participating in a bloody stabbing.     Police investigators

acquired a warrant to search Salie's apartment for "any bloody
                                                                    28


clothing, hairs, any trace of blood that may be found in the

apartment."    They searched the apartment for over one hour,

during which time they confiscated hair from the couch and also

performed tests for blood on the couch.    Despite this search,

police recovered no evidence indicating that the victim had ever

been present in Salie's apartment, and the towels were the only

evidence seized from Salie's apartment that corroborated his

testimony.     We think that the absence of any physical evidence

supporting Salie's testimony likely would have carried real

weight in the jury's deliberations.

    Finally, the judge observed that "there was other evidence

implicating Cowels and Mims."    The Commonwealth takes this

argument a step further.    It contends there is no substantial

risk that the outcome of the trial would be different in the

absence of the towels because "the Commonwealth's case against

the defendants was . . . strong."

    To address this argument, we must clarify the proper

approach to assessing a motion for a new trial on the basis of

newly discovered evidence.     We have observed that "[t]he

strength of the case against a criminal defendant . . . may

weaken the effect of evidence which is admittedly newly

discovered."    Commonwealth v. Grace, 397 Mass. 303, 306 (1986).

See Commonwealth v. Moore, 408 Mass. 117, 127 (1990).     In

considering the over-all strength or weakness of the
                                                                    29


prosecution's case, however, a reviewing court must ensure that

its focus remains on whether, in light of "a full and reasonable

assessment of the trial record," the evidence at issue "would

have played an important role in the jury's deliberations and

conclusions."    Commonwealth v. Tucceri, 412 Mass. at 414.   The

over-all strength or weakness of the evidence presented against

a defendant is significant, therefore, because it provides the

context within which to assess whether the newly discovered

evidence would have been a real factor in the jury's

deliberations.    Where a case is "a weak one for conviction," for

instance, a jury is more likely "to pay attention to collateral

factors and even to make them decisive," and thus a court is

more likely to conclude that evidence relating to one of these

factors was or would have been a real factor in the jury's

deliberations.   Commonwealth v. Bennett, 43 Mass. App. Ct. 154,

162 (1997).

    The analysis remains focused, however, on "what effect the

omission might have had on the jury."    Commonwealth v. Tucceri,

412 Mass. at 411.    "[O]ur inquiry is not whether the verdict may

have been different, but whether the evidence in question

probably served as a real factor in the jury's deliberations."

Commonwealth v. Sullivan, 469 Mass. at 353.    Where we determine

that newly discovered evidence likely would have functioned as a

real factor in the jury's deliberations, or (as in this case)
                                                                    30


that subsequently discredited evidence likely did function as a

real factor, we may not then assess whether the jury still would

have reached the same conclusion.    Instead, the determination

that the evidence likely was a real factor in the jury's

deliberations demands a new trial.    We have justified this

approach as "preserv[ing], as well as it can in the

circumstances, the defendant's right to the judgment of his

peers," since it ensures that the court's analysis turns on

"what effect the omission might have had on the jury," rather

than on "what . . . impact the late disclosed evidence has on

the judge's personal assessment of the trial record."

Commonwealth v. Tucceri, supra at 411.

    Here, although the Commonwealth asserts that its over-all

case against the defendants was strong, it does not contest that

Salie's testimony was the linchpin.    Without Salie's testimony,

the case against the defendants would not have been strong.       In

light of the unique facts presented here -- given Salie's

importance to the prosecution's case and the towels' status as

one of only a few items of physical evidence that bolstered his

severely beleaguered credibility -- we determine that the towels

likely were a real factor in the jury's deliberations.

Consequently, there is a substantial risk that the newly

available testing excluding the victim and the defendants as
                                                                 31


possible sources of the blood on one of the towels would have

altered the outcome.

    3.   Conclusion.   The judgments of conviction are vacated

and set aside, and the matters are remanded to the Superior

Court for a new trial.

                                    So ordered.
