Court Opinion

ID: 6463322
Source: CourtListenerOpinion
Date Created: 2022-06-25 12:50:26.798012+00
Date Added: 2024-06-11T15:52:21.886386
License: Public Domain

Rubin, J.
(dissenting). This case is controlled by Commonwealth v. Curnin, 409 Mass. 218, 222 n.7 (1991). There the Supreme Judicial Court concluded that, because DNA testing “has too great a potential for affecting a jury’s judgment . . . we would not permit the admission of test results showing a *520DNA match (a positive result) without telling the jury anything about the likelihood of that match occurring.”1 Thus, “expert testimony concerning a DNA match [must] be accompanied by information indicating the probability that the match in question might have occurred by chance.” Commonwealth v. Thad, 59 Mass. App. Ct. 497, 505-506 (2003).
DNA testing operates by comparing DNA evidence with a known examplar of the DNA of a particular person. The DNA is compared by examining the alleles at certain specific loci, chosen because of their variability among the human population, see Curnin, supra at 228, to see if the alleles at those loci are the same as the alleles at those loci on the exemplar. See Commonwealth v. Vao Sok, 425 Mass. 787, 790 (1997). Thus, for example, one DNA test permits an examination of the alleles at six loci; another at thirteen loci, as well as a gender identification locus. See State v. Salmon, 89 S.W.3d 540, 544 (Mo. Ct. App. 2002). If a single person’s DNA is tested, and a sufficient number of loci are compared, and if the alleles at all of the loci correspond to an individual’s exemplar, one can make an identifying match, calculating that there is an astronomically high likelihood that the individual who provided the exemplar was the source of the DNA. If at any locus there is not a match, the individual can be excluded as the source of the DNA.
The defendant’s DNA was not found on anything inside the victim’s apartment. It was found on what was conceded to be his own sweatshirt — one he claimed not to have himself been wearing on the day of the crime — which was found in a trash can. (A witness testified that he had seen the defendant wearing the sweatshirt that morning and on the way to and inside a bank about an hour before the attack; a picture of the defendant taken at the bank showed that he was not wearing it.) The victim’s *521DNA was not found on any of the clothing the defendant was wearing at the time of his arrest on the day the crime occurred.
Over the defendant’s objection, the Commonwealth’s expert testified that mixtures of DNA were found on the defendant’s sweatpants and on the inside doorknob of the victim’s apartment. She testified first about how DNA testing kits work. The expert’s testimony related essentially to matching alleles at certain DNA loci found in the mixtures with the alleles at the same loci in DNA exemplars from the victim and the defendant.2 An excerpt of her testimony, which refers to two charts that were introduced in evidence, will give a sense of her testimony:
“For the known sample for [the defendant], it’s the same locations that I mentioned in the previous [known] sample [from the victim], and the numbers are 16, 16 for [location] D3.
“14, 18 for VWA [location],
“18, 25 for FGA [location].
“For gender, it’s an ‘X’ and ‘Y’, representing male.
“At V8, there’s a 10 and 14.
“At V21, it’s 31 and 31.2.
“D18 is 12 and 15.
“D5 is 12 and 13.
“D13 is 11 and 13.
“D7 is 8 and 11.”
She testified that the mixture on the doorknob was “a mixture of DNA consistent with [that of the defendant] and [that of the victim].” She said that the defendant “is included as a potential contributor of the major male profile in the DNA mixture” and *522that the DNA in the mixture on the doorknob was “concordant with” the defendant’s DNA. She said:
“Now, the samples that are concordant with the second known sample, which is from [the defendant], include the sweatshirt front. You can see that at each location . . . each of these numbers are represented .... And again, it’s repeated here, as a single source, in the t-shirt, all the numbers are represented again.
“Then, we get to the mixture sample. And in this situation, with the swab of the doorknob, the numbers here are represented as being concordant with those that are bolded in the sample: 16, 14, 18, and so on.
“Then, in this sample of the sweatpants, at the bottom, there wasn’t enough DNA of that minor contributor to be able to make a comparison to the known sample of [the defendant]. So, there has been no conclusion made; only to the major profile which is represented in the bold.”
She also testified that the victim was “included as a potential source” of some of the mixture on the defendant’s sweatpants. Her detailed testimony was as follows: “Then, also, there’s the next mixture, which is the sweatpants. And in this situation, you can see that the numbers that are concordant with [the victim’s] profile, this time it’s the major profile. So, the numbers, here, are bolded; the 17, 18 is the same. The 17, 19. The 20, 21, and so on.”
The expert did not indicate what the statistical probability was that the defendant contributed to the doorknob mixture or the victim to the sweatpants mixture. The jury did not know. We do not know. With respect to the doorknob, the court says, ante at 516, that “at various sites on the DNA band [the expert] found the alleles that one with the defendant’s DNA profile would leave but other alleles as well, with the result that the defendant could not be excluded as a source of the DNA . . . .”
Does this mean that half the people in the world could have left the DNA that was found in the mixture? Does it mean that only one in a billion could? We have no idea. But the court concluded in Curnin that where DNA evidence is used by the *523prosecution, there is a substantial risk that the evidence could be mistakenly understood definitively to implicate the defendant, here, for example, placing him inside the victim’s apartment. See id. at 219, 222 n.7, 227. Indeed, although there is no information in the record about how likely it is that the alleles found in the swab from the victim’s apartment came from the defendant, the Commonwealth itself in its brief actually treats the DNA evidence as definitive, saying the defendant’s “DNA, albeit a mixture of DNA and not a match, was found on the interior doorknob of the victim’s apartment.”
Because of Curnin, this DNA mixture evidence should not have been admitted “without telling the jury anything about the likelihood of th[e] match” occurring between the alleles found on the doorknob and the alleles in the defendant’s sample and between the alleles found on the sweatpants and the alleles in the victim’s sample. Id. at 222 n.7. Commonwealth v. McNickles, 434 Mass. 839, 854 (2001), is not to the contrary. There, the Supreme Judicial Court upheld the introduction of a DNA test result like that at issue here — that “did not amount to or purport to be an actual identification of the defendant,” but “yielded only descriptive information concerning the perpetrator.” The court explained that “[i]f the Commonwealth’s expert’s view were accepted by the jury, the descriptive information from the test was the perpetrator’s genotype at that one site (a homozygous 4.2/3), a trait shared by the defendant and many members of the general population.” Ibid. But, in that case, as the court noted, the expert’s testimony addressed how many individuals shared that DNA trait.3 The McNickles case does not suggest that the introduction of DNA test results short of an identifying match does not require that the jury be provided with some basis for understanding the probability they represent. *524And other jurisdictions that require statistical information to accompany DNA evidence do so where the evidence is something less than an identifying match. See, e.g., People v. Coy, 243 Mich. App. Ct. 283 (2000); Armstead v. State, 342 Md. 38 (1996). Indeed, because of “the usual astronomical improbabilities of others being the source of the DNA” when an identifying match is found, ante at 515, it would seem that the rule requiring that DNA evidence be accompanied by statistical information is of the most importance in cases like this where the statistical probability that the DNA sample tested came from a particular source is substantially lower than where DNA evidence is sufficient to provide a match that actually identifies the defendant as the perpetrator. See Young v. Maryland, 388 Md. 99, 110-117, 119-120 (2005) (distinguishing Armstead v. State, supra, and holding that although supporting statistics are required when DNA evidence falling short of an identifying match is admitted, “|w]hen the random match probability is sufficiently minuscule, the DNA profile may be deemed unique. In such circumstances, testimony of a match is admissible without accompanying contextual statistics”).
Expert testimony concerning a match of some alleles in a DNA mixture, like expert testimony concerning an identifying DNA match, must be accompanied by statistical information indicating the probability that the match might have occurred by chance. Because the DNA evidence here was not accompanied by such information, the defendant is entitled to a new trial. I therefore respectfully dissent.

On this record, it does not appear that the test results in this case can be characterized as the kind of “inconclusive” ones that would have been inadmissible because they were not “probative of an issue of consequence in the case.” Commonwealth v. Nesbitt, 452 Mass. 436, 254 (2008). See ibid, (describing testimony that defendant “couldn’t be excluded” as a potential match for DNA evidence where no one could be excluded because the DNA could have come from anyone).

Detailed descriptions of DNA evidence and methods of DNA analysis can be found in a number of cases, including Commonwealth v. McNickles, 434 Mass. 839 (2001), and Armstead v. State, 342 Md. 38 (1996).

“The frequency of a homozygous 4.2h at the DQA1 site varies from a low of one in 1,000 in the Caucasian population, to one in 100 in the African-American population, to as high as one in eighty-three in the Hispanic population. Defense counsel’s cross-examination of [the Commonwealth’s expert] walked through the arithmetic of how many out of 1,000 African-Americans, 10,000 African-Americans, 100,000 African-Americans, and one million African-Americans would have this same genotype, and then pointedly asked her if she knew how many African-Americans lived in Boston.” Id. at 854 n.26.