Case report: Coincidental inclusion in a 17-locus Y-STR mixture, wrongful conviction and exoneration. (November 2017)

• Record Type: Journal Article
• Authors: Hampikian, Greg; Peri, Gianluca; Lo, Shih-Shiang; Chin, Mong-Hwa; Liu, Kuo-Lan
• Is Part Of: Forensic science international. Volume 31(2017)
• Page Start: 1
• Page End: 4
• Publication Date: 2017-11
• Subjects: Coincidental inclusion -- Y-STR -- DNA mixture -- Complex DNA -- Exoneration -- Innocence; Forensic genetics -- Periodicals; Génétique légale -- Périodiques; Forensic genetics; Electronic journals; Periodicals; 614.1
• DOI: 10.1016/j.fsigen.2017.08.004
• Languages: English
• ISSNs: 1872-4973

Abstract

Highlights: A coincidental match to a 17-locus Y-STR mixture led to a wrongful conviction. Expansion from 17 to 23 loci Y-STR test, excluded suspect and led to an exoneration. Likelihood ratios must consider all relevant hypotheses. Abstract: We report the case of a suspect (Suspect-3) who was convicted (and later exonerated) of participating in the multiple-attacker rape of two women. The forensic evidence against him was his inclusion in a 17-marker Y-STR mixture isolated from semen on one victim's clothing. The DNA inclusion produced a match statistic with a combined probability of inclusion of 1 in 741, and a Likelihood Ratio of 3296. While the defense team was told that Suspect-3 was included in the semen DNA mixture, they were not told that all of the Y-STR alleles could also be explained by just the other two accused attackers' haplotypes. Suspect-3 was subsequently freed after the Taiwan Association for Innocence requested re-examination of the incriminating mixed DNA sample. The Criminal Investigation Bureau was then able to exclude him using an extended set of Y-STR markers (23 loci), leading to his exoneration.