The Current Status of Microscopical Hair Comparisons

Abstract

Although the microscopical comparison of human hairs has been accepted in courts of law for over a century, recent advances in DNA technology have called this type of forensic examination into question. In a number of cases, post-conviction DNA testing has exonerated defendants who were convicted in part on the results of microscopical hair comparisons. A federal judge has held a Daubert hearing on the microscopical comparison of human hairs and has concluded that this type of examination does not meet the criteria for admission of scientific evidence in federal courts. A review of the available scientific literature on microscopical hair comparisons (including studies conducted by the Royal Canadian Mounted Police and the Federal Bureau of Investigation) leads to three conclusions: (1) microscopical comparisons of human hairs can yield scientifically defensible conclusions that can contribute to criminal investigations and criminal prosecutions, (2) the reliability of microscopical hair comparisons is strongly affected by the training of the forensic hair examiner, (3) forensic hair examiners cannot offer estimates of the probability of a match of a questioned hair with a hair from a randomly selected person. In order for microscopical hair examinations to survive challenges under the U.S. Supreme Court’s Daubert decision, hair microscopists must be better trained and undergo frequent proficiency testing. More research on the error rates of microscopical hair comparisons should be undertaken, and guidelines for the permissible interpretations of such comparisons should be established. Until these issues have been addressed and satisfactorily resolved, microscopical hair comparisons should be regarded by law enforcement agencies and courts of law as merely presumptive in nature, and all microscopical hair comparisons should be confirmed by nuclear DNA profiling or mitochondrial DNA sequencing.

Human hair shaft proteomic profiling: individual differences, site specificity and cuticle analysis

“…Nevertheless, the search for more objective criteria by which to judge hair matches continues ( Taupin, 2004 ). Hair evidence is ordinarily supplemented by DNA evidence whenever possible ( Rowe, 2001 ). When follicle tissue is present, nuclear DNA extracted from a hair sample may identify the donor.…”

What determines the success of the species identification? The identification of 10 deer (Cervidae) species in China based on multiple parameters of hair morphology

“…Within a family or genus, it is difficult to successfully discriminate species by means of only a single medullar or cuticular scale pattern. Wildlife forensic medicine has been working on discriminating animal hair using multivariate morphological function to improve discriminant accuracy (Oli 1993, Rowe 2001, Anwar et al 2011, Kerley et al 2015. Sato et al (2006) obtained a discriminant rate of 96% and 99% for cat hair and dog hair, respectively, with 13 hair parameters.…”

“…* discriminate species by means of only a single medullar or cuticular scale pattern. Wildlife forensic medicine has been working on discriminating animal hair using multivariate morphological function to improve discriminant accuracy(Oli 1993, Rowe 2001, Anwar et al 2011, Kerley et al 2015.Sato et al (…”

Murder in the Archives: Additions to the Sydney Smith Collection

“…Furthermore, Smith confi rmed that the hairs taken from the wooden portion of the axe matched 'in all details' to the sample taken from the victim; these would have been compared microscopically to identify similarities in colour, structure and cuticular traits between the hair taken from the axe to those taken from the victim. 19 A reconstruction of the skull was also undertaken by Smith, and in his evidence he notes that signifi cant cracking and shattering of the bone was observable. When questioned further Smith acknowledged that the resultant injuries would have been caused by some considerable force and that the reconstruction of the skull showed that the axe fi tted exactly with the injuries.…”

“…12 Marr was arrested for the murder of his colleague Mary Ann Mills who was found dead at their place of occupation, a framing workshop on Rose Street, Edinburgh. Short articles covering the trial of this case were identifi ed in The Scotsman, 19 February 1929, and The Aberdeen Press and Journal, 20 February 1929, but a second article in The Scotsman, 20 February 1929, provides the greatest detail of the evidence given. The article indicates a plea of insanity was put forth by the defendant and outlines the evidence provided in support of this.…”