Commonwealth v. Bryan Diaz.

CourtMassachusetts Appeals Court
DecidedFebruary 28, 2025
Docket23-P-1032
StatusUnpublished

This text of Commonwealth v. Bryan Diaz. (Commonwealth v. Bryan Diaz.) is published on Counsel Stack Legal Research, covering Massachusetts Appeals Court primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Commonwealth v. Bryan Diaz., (Mass. Ct. App. 2025).

Opinion

NOTICE: Summary decisions issued by the Appeals Court pursuant to M.A.C. Rule 23.0, as appearing in 97 Mass. App. Ct. 1017 (2020) (formerly known as rule 1:28, as amended by 73 Mass. App. Ct. 1001 [2009]), are primarily directed to the parties and, therefore, may not fully address the facts of the case or the panel's decisional rationale. Moreover, such decisions are not circulated to the entire court and, therefore, represent only the views of the panel that decided the case. A summary decision pursuant to rule 23.0 or rule 1:28 issued after February 25, 2008, may be cited for its persuasive value but, because of the limitations noted above, not as binding precedent. See Chace v. Curran, 71 Mass. App. Ct. 258, 260 n.4 (2008).

COMMONWEALTH OF MASSACHUSETTS

APPEALS COURT

23-P-1032

COMMONWEALTH

vs.

BRYAN DIAZ.

MEMORANDUM AND ORDER PURSUANT TO RULE 23.0

After a jury trial in the Superior Court, the defendant was

convicted of armed assault with intent to murder, G. L. c. 265,

§ 18 (b) (2014); aggravated assault and battery by means of a

dangerous weapon resulting in serious bodily injury, G. L.

c. 265, § 15A (c) (i); assault and battery by discharging a

firearm, G. L. c. 265, § 15E (2015); unlawful possession of a

loaded firearm, G. L. c. 269, § 10 (n) (2015); and unlawful

possession of a firearm, G. L. c. 269, § 10 (a) (2015).1 On

appeal, the defendant argues that the judge abused her

discretion by admitting prejudicial testimony from the

1The defendant was also found guilty of unlawful possession of ammunition. That charge was dismissed at sentencing at the request of the Commonwealth "as merged." Commonwealth's gang expert, Sergeant Stephen Roche of the

Worcester police department. We affirm the convictions.

Background. The following facts are not disputed. The

defendant was indicted in connection with a 2018 drive-by

shooting in Worcester. Although the police had some evidence

that the defendant was the shooter, the culprit's identity

remained a live issue at the time of trial.

The Commonwealth's theory of the case included evidence of

the defendant's motive to commit the crimes. To that end, the

prosecution moved in limine to introduce Roche's expert opinion

evidence to show that the defendant and the victim, Michael

Diaz, were members of rival gangs, and to support the

Commonwealth's argument that the shooting was part of a spike in

local gang-related violence. The defendant opposed the

Commonwealth's motion and cross-moved to exclude evidence of his

gang membership, arguing that the proposed testimony was

inadmissible propensity evidence.

The judge conducted a voir dire to assess the foundation of

Roche's opinions. On direct examination, Roche testified that

he had been a Worcester police officer for thirty-four years and

had worked in the gang unit for twenty-two years. He also

testified that the members of the gang unit identify local gang

members using "a ten[-]point system," under which certain

evidence of gang membership -- for example, a person's self-

2 identification as a gang member -- is valued in "points" and

contributes to an overall score. An individual who scores ten

or more points is deemed to be an active gang member.

At the motion hearing, Roche testified to his familiarity

with local gangs and gang rivalries in Worcester, and to the

increase in gang-related violence in Worcester in the period

leading up to the shooting. In particular, he testified that

the Kilby and MOB gangs were rivals, and that rival gangs

engaged in frequent retaliation against one another.

Roche opined that the defendant belonged to the Kilby gang,

and that the victim was a member of the MOB gang; this opinion

relied on verification performed in 2014 by another member of

the Worcester gang unit, Officer Thomas Duffy, using the ten-

point system noted above. Moreover, Roche's testimony confirmed

his awareness that both the defendant and the victim had

previously "self-identified" as members of those gangs to Duffy

and, separately, to staff at the house of correction.

Specifically, Roche testified that a corrections officer, John

Sables, told him that the defendant and the victim confirmed

their memberships in the Kilby and MOB gangs, respectively, as

part of each individual's intake at the house of correction in

3 2014.2 At the hearing, the defendant did not challenge the

validity of the ten-point system Roche described in his

testimony, nor -- with one exception as to hearsay that the

defendant appears to have withdrawn -- did he object to the

substance of any of Roche's testimony.

At the conclusion of the voir dire, the judge allowed the

Commonwealth's motion to present Roche's expert testimony,

subject to carefully-tailored limitations set forth in a

detailed written order. Notably, the judge ruled that Roche

could testify to his opinion that the defendant and the victim

belonged to rival gangs, but that the Commonwealth could not

elicit from him any testimony about the methodology on which he

relied in forming that opinion, unless the issue was raised by

the defendant on cross-examination. The judge explicitly stated

that, at any party's request, she would give limiting

instructions that the only permissible use of the expert

testimony was to motive, and at trial, she did so. Roche

testified in accordance with the judge's order.3

2 Roche was not asked about the context in which the defendant and the victim self-identified to Duffy. He did, however, testify that correctional personnel collect information from detainees about their gang affiliations to ensure the jail does not house rival gang members together.

3 At trial, the defendant did not discuss the methodology underpinning Roche's opinion.

4 Discussion. The defendant argues that Roche's expert

testimony was inadmissible on various grounds. We address each

in turn.

1. Daubert-Lanigan challenge to expert testimony. The

defendant's challenge to the reliability of the "ten-point"

system Roche used to form his opinion on the defendant's gang

membership was not raised below. With no record developed to

support it, the argument fails. See Daubert v. Merrell Dow

Pharms., Inc., 509 U.S. 579, 589 (1993); Commonwealth v.

Lanigan, 419 Mass. 15, 24 (1994); Commonwealth v. Coutu, 88

Mass. App. Ct. 686, 693-694 (2015).

We are not persuaded by the defendant's related arguments.

First, we do not agree that Roche's opinion lacked an adequate

foundation. It is well settled that "an expert's opinion must

be based on (1) facts within his or her direct personal

knowledge, (2) evidence already in the record, or (3) facts or

data not in evidence if the facts or data are independently

admissible in evidence and are a permissible basis for an expert

to consider in formulating an opinion" (emphasis added). Matter

of P.R., 488 Mass. 136, 142 (2021). These are disjunctive

requirements; as we discuss infra, Roche's opinion rested on

independently admissible evidence tying the defendants to

specific gangs, and it therefore had sufficient foundation. See

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Related

Sgro v. United States
287 U.S. 206 (Supreme Court, 1932)
Daubert v. Merrell Dow Pharmaceuticals, Inc.
509 U.S. 579 (Supreme Court, 1993)
Davis v. Washington
547 U.S. 813 (Supreme Court, 2006)
Commonwealth v. Atchue
471 N.E.2d 91 (Massachusetts Supreme Judicial Court, 1984)
Commonwealth v. Coutu
88 Mass. App. Ct. 686 (Massachusetts Appeals Court, 2015)
Commonwealth v. Lanigan
641 N.E.2d 1342 (Massachusetts Supreme Judicial Court, 1994)
Commonwealth v. Larkin
708 N.E.2d 674 (Massachusetts Supreme Judicial Court, 1999)
Commonwealth v. Maldonado
709 N.E.2d 809 (Massachusetts Supreme Judicial Court, 1999)
Commonwealth v. Nardi
893 N.E.2d 1221 (Massachusetts Supreme Judicial Court, 2008)
Commonwealth v. Avila
912 N.E.2d 1014 (Massachusetts Supreme Judicial Court, 2009)
Commonwealth v. Greineder
984 N.E.2d 804 (Massachusetts Supreme Judicial Court, 2013)
Commonwealth v. Lester
872 N.E.2d 818 (Massachusetts Appeals Court, 2007)
Chace v. Curran
881 N.E.2d 792 (Massachusetts Appeals Court, 2008)
Commonwealth v. Wardsworth
124 N.E.3d 662 (Massachusetts Supreme Judicial Court, 2019)

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Commonwealth v. Bryan Diaz., Counsel Stack Legal Research, https://law.counselstack.com/opinion/commonwealth-v-bryan-diaz-massappct-2025.