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Forensic DNA Analysis: An Introduction

M.W. Perlin, A. Krastek and M. Collins, "Forensic DNA analysis: An introduction", Duquesne University Forensic Friday, Pittsburgh, PA, 8-Oct-2010.


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Three Lectures

Download Judge Martin's TrueAllele admissibility ruling


Abstract

On Friday, October 8, Dr. Mark Perlin, CEO and chief scientific officer of Cybergenetics, Senior Deputy Attorney General Anthony Krastek, and Allegheny County Assistant Public Defender Michelle Collins will be teaching a Continuing Legal Education (CLE) course on "Forensic DNA Analysis: An Introduction" at Duquesne University in The Cyril H. Wecht Institute of Forensic Science and Law.

The course will introduce computer interpretation of DNA evidence, and its courtroom admissibility. The case example is the recent Blairsville dentist homicide, where a computer extracted more DNA identification information than the FBI's review.

On the night of April 12, 2006, dentist John Yelenic was brutally murdered in his Blairsville, PA home. A year later, Pennsylvania State Trooper Kevin Foley, boyfriend of Dr. Yelenic's estranged wife, was charged with the crime. Under the victim's fingernails was a mixture of DNA containing mainly the victim, plus a trace amount (6.7%) of an unknown contributor.

The FBI's interpretation of the DNA evidence gave a 13,000 chance of match with Foley, relative to a random person. Considering that almost 13 million people reside in Pennsylvania, this was not an overwhelming statistic. However, some mixture interpretation methods can make better use of the DNA data for a more informative result.

Prosecutor Krastek asked Dr. Perlin to re-examine this DNA mixture using Cybergenetics TrueAllele® computer approach. The computer mathematically processed the fingernail DNA data, and found a match statistic of 189 billion. The prosecution also asked Dr. Robin Cotton, the former Cellmark lab director, to conduct an independent human review of the DNA evidence. Her method yielded a match statistic of 23 million.

On February 18, 2009, there was a pretrial hearing in Indiana County on the admissibility of the two outside expert DNA evidence interpretations. SDAG Krastek presented the relevant law and case precedents. Drs. Perlin and Cotton each explained the scientific foundations of their respective methods to the court, and were cross-examined at length. Judge William Martin ruled that their DNA interpretation methods were based on generally accepted methods in the relevant scientific community, pursuant to the Frye rule and Rule 702.

The Commonwealth v. Foley case was the first time that advanced mathematical computing was used in a trial for interpreting DNA evidence. Dr. Perlin and SDAG Krastek will describe the science and law of how this testimony was introduced. The course will:

(1) explain the nature of DNA evidence, and its accurate scientific interpretation;

(2) walk through the homicide events, using computer crime scene reconstruction;

(3) show how to present scientific DNA evidence in court, in a simple, understandable way; and

(4) teach how to establish admissibility in court for DNA mixture interpretation methods.