Sunday, December 6, 2015

Hair Evidence in the “Clearly Not Exonerated” Exoneration of Mark Reid

On November 3, the fictional forensic scientist in the world’s most watched television drama was aghast that she had once performed microscopic hair comparisons. Having learned that such comparisons are entirely discredited, NCIS’s Abby Sciuto is horrified: “Can you imagine if I messed up, what that really means? It means that innocent people went to jail because of me, because of my mistakes.” As a writer for Entertainment Weekly wrote, “Abby’s spinning out of control, locked in her lab and reexamining every single case she’s ever touched.” 1/

The “16 Years” episode is fiction, but real people have gone to jail for longer than that — and some could have been executed — because of mistakes by examiners. One disturbing hair-comparison case is State v. Reid. 2/ I have cited the Connecticut Supreme Court's opinion in two publications that survey different ways to testify about the implications of similarities between trace evidence and samples from known sources (such as the defendant). 3/ In doing so, I was not expressing the slightest agreement with the supreme court’s reasoning or arguing that the court was correct to hold that the trial judge properly admitted the testimony. But the case does illustrate how a careful criminalist called upon to testify could proceed in the face of gaping scientific uncertainty about the significance of similarities in the trace material and the known samples. It also illustrates the different sorts of errors than can occur in ascertaining hair morphology and drawing inferences from it as well as the different types of exonerations that can occur with the benefit of DNA testing.

I. The Criminalist Gives “Features Only” Testimony in Reid

It seems hard to deny that various physical features of hair display at least some variation within a population.  But without extensive population data that might permit at least rough estimates of the relative frequencies of the features, and without employing methods that have demonstrated reliability in measuring the features of interest, it is not clear how, or even if, this information should be used in trials.

One possibility is to limit the testimony to a presentation of the observed features (and perhaps a characterization of the samples' features as similar or different, as the case may be). According to the Connecticut Supreme Court, the analyst in Reid pursued this “features only” approach:
[He] displayed an enlarged photograph of one of the defendant's hairs and one of the hairs recovered from the victim's clothing as they appeared side-by-side under the comparison microscope. [He] explained to the jurors how the hairs were similar and what particular features of the hairs were visible. He also drew a diagram of a hair on a courtroom blackboard for the jurors. The jurors were free to make their own determinations as to the weight they would accord the expert's testimony in the light of the photograph and their own powers of observation and comparison.
The trial court had held a pretrial hearing to decide whether this testimony satisfied the preliminary showing of scientific validity normally required of all suitably challenged scientific evidence. The court found that it did, but the supreme court did not rely on or discuss either the scientific validity or the general scientific acceptance of visual hair comparisons. It avoided the issue by holding that the testimony did not have to satisfy such standards — because it was not “scientific evidence” at all. Rather, the expert “testified about a subject that simply required the jurors to use their own powers of observation and comparison.”

Three years later, in 2003, the Superior Court granted a petition for a new trial. 4/ Its opinion casts doubt on the no-science theory. Elaborating on the supreme court’s description of the testimony, this court observed that at the trial, the expert “indicated that hair comparison analysis ... is generally accepted as reliable within the field of forensic science” and “that he could state, ‘to a reasonable degree of scientific certainty,’ that the pubic hairs found on the victim's clothing were microscopically similar to those pubic hair samples taken from Mark Reid.” On such a record, the supreme court’s conclusion that the usual standards for scientific evidence are beside the point is hard to swallow.

II. The Superior Court Orders a New Trial While Insisting that the DNA Evidence Does Not Exonerate Reid

In any event, at Reid’s trial
Mr. Settachatgul testified that the three hairs recovered from the victim's clothing were pubic hairs. These hairs were rootless, indicating that they were shed, not plucked; one was found on the victim's jeans, another on a sock, and another on her lower undergarment (panty). ... Based on the microscopic analysis, Mr. Settachatgul's conclusion was that the three rootless hairs recovered from M.'s clothing were Negroid pubic hairs which had similar characteristics to the pubic hairs supplied by petitioner.
As the State’s Attorney explained in her summation, “the hairs ... appeared to be the same color, both had an abundance of fuci, and both exhibited the shadow of twisting, indicative of pubic hair.”  However, she acknowledged that “statistics are not done in the comparison field, [and] the only conclusion that can be drawn is similar or dissimilar characteristics, not the percentage of the population which shares those hair characteristics.” She told the jury “this is not conclusive evidence. I agree with the defense to that degree. It is not conclusive. But it is supportive of the victim's I.D.”

This support collapsed when postconviction mitochondrial DNA testing established that the three public hairs came from the same individual or from individuals in the same maternal lineage. Critically, Reid was not in that maternal line, while the victim, a white woman, was. This left two major possibilities: either the unknown rapist was the source of the three hairs or the victim was. The former scenario totally exculpates Reid; the latter renders the “supportive” expert testimony inconclusive.

Reid argued that the mtDNA test proved his actual innocence — that the criminalist’s determination of race had to be true, that the victim was white, and therefore the true rapist must have been some other black man who deposited three hairs on the victim’s clothes. The court did not buy this argument. And for good reason. Because the mtDNA testing showed that the victim’s mtDNA sequences matched those of the three hairs, the most plausible conclusion is that the criminalist erred in finding “Negroid pubic hairs.” The hairs probably were the victim’s rather than any rapist’s.

Thus, nothing was left of to connect Reid to the rape except the victim’s identification of him. The Superior Court concluded:
This is a close, difficult case. The new mtDNA evidence merely excludes petitioner as the depositor of the unknown hairs; it clearly does not exonerate him. And, as stated, the victim, M., was certain and steadfast in her identification of Mark Reid, and the circumstances surrounding that identification support its reliability, at least when viewed absent the newly discovered mtDNA evidence.
There are reasons to question this rosy picture of the eyewitness testimony, but whatever one thinks of that identification, the Superior Court found that Reid was entitled to a new trial at which he could use the mtDNA evidence to devastate a major part of the state’s case — the hair testimony.

III. The End of the Story Leaves Questions Hanging

In the end, there was no retrial. According the University of Michigan Law School’s National Registry of Exonerations, the state dismissed the charges “after the victim declined to participate ... . Reid, who had other felony convictions, was deported to his native Jamaica. In 2004, Reid filed a lawsuit seeking $2 million in damages from East Hartford.” The Registry does not report the outcome of that action. 5/

Whether or not all microscopic hair testimony is scientifically invalid because the comparisons have not been shown to be scientifically reliable, there is agreement that criminalists frequently have erred by using the similarity between hairs to make strong or quantified statements about the source of the trace hairs. 6/ This type of overclaiming apparently did not occur in Reid. In granting a new trial, the Superior Court emphasized that “Mr. Settachatgul was testifying only to the very ‘narrow opinion’ that the three pubic hairs recovered from the victim's clothing were similar to the samples obtained from the defendant, and, that he, Settachatgul could not say that the questioned specimens were the pubic hairs of petitioner/defendant.”

This testimony would not be judged as scientifically invalid under the FBI’s guidelines for reviewing microscopic-hair-comparison testimony. 7/ Likewise, the prosecutor’s summation was not infected with the sort of egregious overstatements, such as “There is one chance, perhaps for all we know, in 10 million that it could [be] someone else’s hair,” heard in other cases. 8/

The hair analyst may have erred in concluding that the features were similar. But mtDNA testing cannot tell us that. The small DNA molecules in the mitochondria do not relate to hair morphology. They provide a complementary — and more specific — test for identity. Sequence differences can exclude suspects when the inherently less discriminating visible features cannot. Standing alone, this limitation does not make microscopic hair analysis scientifically invalid, and it does not mean that the analyst misjudged the visual features here. But it does underscore the need to estimate the likelihoods or conditional error rates for microscopic hair comparisons. Without this information, how can anyone know what weight to give to the criminalist’s findings of similar hairs?

Finally, given the mitochondrial results for the victim and the pubic hairs in Reid, the hair analyst probably erred in concluding that the three pubic hairs were of “Negroid origin.” As noted earlier, the woman who was attacked in Reid was white, and the simplest conclusion is that the hairs on her clothes were hers, as the mtDNA sequences suggest. Furthermore, the unqualified assurance as to the racial origin of the hairs was unjustified — even if the classification turned out to be correct. Skimming a few forensic science textbooks, I can find no reference to publications in the scientific literature to support the position that hair analysts can make firm determinations of biogeographic ancestry. Caution is usually advised. 9/

  1. Sara Netzley, “16 Years,” Entertainment,
  2. 757 A.2d 482 (Conn. 2000). The case is noted in J.M. Taupin, Forensic Hair Morphology Comparison— A Dying Art or Junk Science?, 44 Sci. & Justice 95 (2004).
  3. David H. Kaye, David E. Bernstein & Jennifer L. Mnookin, The New Wigmore: A Treatise on Evidence: Expert Evidence (2d ed. 2011); David H. Kaye, Presenting Forensic Identification Findings: The Current Situation, in Communicating the Results of Forensic Science Examinations 12–30 (C. Neumann et al. eds. 2015) (Final Technical Report for NIST Award 70NANB12H014).
  4. Reid v. State, No. CV020818851, 2003 WL 21235422 (Ct. Super. Ct. May 14, 2003).
  5. Maurice Possley, Mark Reid, The National Registry of Exonerations.
  6. David H. Kaye, Ultracrepidarianism in Forensic Science: The Hair Evidence Debacle, 72 Wash. & Lee L. Rev. Online 227 (2015)
  7. Id.
  8. Spencer S. Hsu, Santae Tribble Cleared in 1978 Murder Based on DNA Hair Test, Dec.14, 2012 (quoting from federal prosecutor David Stanley’s closing argument).
  9. Max M. Houck & Jay A. Siegel, Fundamentals of Forensic Science 303 (2015) (“Estimating the ethnicity or ancestry of an individual from his or her hairs is just that: an estimate.”); Richard Saferstein, Forensic Science: An Introduction 419 (2d ed. 2011) (“all of these observations are general, with many possible exceptions. The criminalist must approach the determination of race from hair with caution and a good deal of experience.”).
Acknowledgment: Thanks to Chris Fabricant for thoughts on State v. Reid and for pointing me to the full history of the case.

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