DNA Exposed Flaws in Many Forensic Mainstays


In a series of brief video documentaries, the New York Times looks back at some of the flawed forms of criminal evidence, including microscopic hair analysis, a staple of forensics for generations. With the advent of DNA analysis in the late 1980s, apparent matches of hair samples ultimately proved to be not quite as flawless as people had been led to believe. The story cites the case of Kirk Odom, a Washington man who was found guilty of rape in 1981 and spent two decades behind bars. The FBI's vaunted crime lab had asserted that hairs taken from his head were virtually indistinguishable from one found on the victim's nightgown.

But DNA testing established that Odom was not the rapist, as he had asserted all along. Other lab techniques have had their reliability in the courtroom called into question. A 2009 report by the National Academy of Sciences found “serious problems” with an assortment of methods routinely relied on by prosecutors and the police, including fingerprinting, blood typing, weapons identification, shoe print comparisons, handwriting, bite marks and hair testing. DNA was the game changer. The 2009 report said that, with the exception of nuclear DNA analysis, “no forensic method has been rigorously shown to have the capacity to consistently, and with a high degree of certainty, demonstrate a connection between evidence and a specific individual or source.”

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