Mass. R. Evid. 1105
Evidence that a third party committed the crimes charged against the defendant, or had the motive, intent, and opportunity to commit the crimes, is admissible provided that the evidence has substantial probative value. In making this determination, the court must make a preliminary finding that the evidence is relevant, is not too remote or speculative, and will not tend to prejudice or confuse the jury. If the evidence is otherwise inadmissible, the court must also find that there are substantial connecting links between the crime charged and a third party or between the crime charged and another crime that could not have been committed by the defendant.
Mass. Guid. Evid. 1105
Third-party culprit evidence-evidence that someone else committed the crime charged, or had the motive, intent, and opportunity to do so-is "a time-honored method of defending against a criminal charge." Commonwealth v. Rosa, 422 Mass. 18, 22 (1996). A defendant possesses a fundamental due process right to present such evidence, Commonwealth v. Jewett, 392 Mass. 558, 562 (1984), and doubts about admissibility should be resolved in the defendant's favor, Commonwealth v. Conkey, 443 Mass. 60, 66 (2004). Because the issue implicates constitutional rights, appellate courts review the decision to exclude third-party culprit evidence independently, rather than for abuse of discretion, and the erroneous exclusion of such evidence, upon proper objection, requires reversal unless harmless beyond a reasonable doubt. Conkey, 443 Mass. at 66-67, 70. See also Commonwealth v. Buckman, 461 Mass. 24, 29-30 (2011) (trial judge had discretion to rule in advance of trial that defendant had not made adequate showing that three potential culprits were connected to the crime, and that defendant should provide advance warning to court before offering evidence or argument at trial of third-party culprit).
Defendants may introduce evidence showing that another person committed the crime charged or had the motive, intent, and opportunity to do so, see Commonwealth v. Silva-Santiago, 453 Mass. 782, 800 (2009); that another person recently committed a similar crime by similar methods, see Jewett, 392 Mass. at 562-563; or that another person in a position to commit the charged crime had previously committed other bad acts that are related to the charged crime, see Conkey, 443 Mass. at 67-70.
While defendants are entitled to wide latitude in introducing third-party culprit evidence, the evidence must be relevant-that is, it must have a rational tendency to prove the issue raised by the defense-and cannot be too remote or speculative. Commonwealth v. Steadman, 489 Mass. 372, 383 (2022). See Commonwealth v. Andrade, 488 Mass. 522, 532-533 (2021) (evidence of ballistics match between shell casing found at scene and shell casing associated with unsolved 2006 murder properly excluded; evidence could have confused jury absent further evidence connecting unsolved murder to individuals involved in defendant's case, and such evidence, even if available, would have created distracting "trial within a trial").
Evidence of a third party's ill will or possible motive to commit the charged crime, standing alone, is insufficient to qualify as third-party culprit evidence. The evidence must also show that the alleged third-party culprit had the intent and opportunity to commit the crime. Commonwealth v. Scott, 470 Mass. 320, 328-329 (2014). Compare Steadman, 489 Mass. at 383 (noting that defendant was permitted to introduce evidence that alleged third-party culprit had loud argument with victim the morning before murder at campground where victim's body was found), and Conkey, 443 Mass. at 70 (reversible error to exclude evidence of alleged third-party culprit's motive to commit sexual assault where third party was victim's landlord, possessed key to her home, and had recently opened lingerie drawer in her bedroom), with Andrade, 488 Mass. at 533 (evidence that rival gang members lived near shooting and were involved in feud with victims not sufficient to support third-party culprit defense where there was no evidence that they had been nearby at time of shooting and only defendant and intended victim were seen holding guns), and Commonwealth v. Rice, 441 Mass. 291, 305-306 (2004) (evidence that alleged third-party culprit had threatened to kill victim more than one year before her murder properly excluded where no other evidence tended to show third party had been involved in murder).
In "rare circumstances," the defendant's constitutional right to present a defense may require the admission of otherwise inadmissible hearsay evidence to establish a third-party culprit defense. Commonwealth v. Drew, 397 Mass. 65, 72 (1986). Such evidence is admissible "only if, in the judge's discretion, the evidence is otherwise relevant, will not tend to prejudice or confuse the jury, and there are other substantial connecting links to the crime." Commonwealth v. Silva-Santiago, 453 Mass. 782, 801 (2009). See Commonwealth v. Morgan, 449 Mass. 343, 358 (2007) (absent witness's statement that third party told her that he had shot victim was not admissible as statement against penal interest or as third-party culprit evidence where statement was not corroborated and third party denied making the statement when interviewed by police); Commonwealth v. O'Brien, 432 Mass. 578, 588-589 (2000) (evidence that victim had expressed fear of third party correctly excluded where there were no substantial links between third party and crime because it amounted to nothing more than witness's opinion that third party committed crime).
A trial judge need not give a specific instruction on third-party culprit evidence so long as the jury instructions, taken as a whole, adequately convey the Commonwealth's burden to prove beyond a reasonable doubt that the defendant committed the crime charged. Commonwealth v. Hoose, 467 Mass. 395, 412-413 (2014). "[T]he Commonwealth does not have the burden to prove beyond a reasonable doubt that some third party is not guilty of the charged crime." Id. at 412.
Rebutting Third-Party Culprit Defense. Where the Commonwealth seeks to obtain a DNA buccal swab from a third party to foreclose a possible third-party culprit defense, it bears the burden of establishing probable cause that a crime has been committed and that the sample probably will provide evidence relevant to the question of the defendant's guilt. Commonwealth v. Kostka, 471 Mass. 656, 659 (2015) (DNA buccal swab of defendant's twin brother).
Admission to Establish Inadequate Investigation. Evidence that does not qualify as third-party culprit evidence may nonetheless be admissible as Bowden evidence, see Commonwealth v. Bowden, 379 Mass. 472 (1980), that is, evidence offered to establish the inadequacy of a police investigation. See Commonwealth v. Silva-Santiago, 453 Mass. 782, 802 (2009) (explaining that "information regarding a third-party culprit, whose existence was known to the police but whose potential involvement was never investigated, may be admissible under a Bowden defense even though it may not otherwise be admissible under a third-party culprit defense").
Section 403, Excluding Relevant Evidence for Prejudice, Confusion, Waste of Time, or Other Reason; Section 1107, Inadequate Police Investigation Evidence.