(Click on image to enlarge). The Federal Bureau of Investigation has formally acknowledged that examiners from the FBI Laboratory’s microscopic hair comparison unit for decades provided flawed forensic testimony purportedly matching crime scene hair evidence to the hair of defendants charged with those crimes. As part of an ongoing review of inaccurate forensic evidence, the FBI admitted that, in the 268 trials examined so far, its forensic experts systematically overstated the certainty of matches between crime scene hair evidence and defendants’ hair. That flawed testimony favored prosecutors more than 95% of the time.

The FBI admitted providing inaccurate expert testimony in 32 capital trials in which defendants were sentenced to death, including 10 cases from Florida and 5 each from Pennsylvania and Texas. Nine of the defendants — including all 5 from Texas — have since been executed.

Studies have shown that inaccurate forensic evidence is frequently present in innocence cases — and improper hair comparison testimony may already have contributed to at least one wrongful execution. Senator Richard Blumenthal, a former prosecutor, said, “These findings are appalling and chilling in their indictment of our criminal justice system, not only for potentially innocent defendants who have been wrongly imprisoned and even executed, but for prosecutors who have relied on fabricated and false evidence despite their intentions to faithfully enforce the law.”

The FBI and the Justice Department said they “are committed to ensuring that affected defendants are notified of past errors and that justice is done in every instance. The Department and the FBI are also committed to ensuring the accuracy of future hair analysis testimony, as well as the application of all disciplines of forensic science.”

The report likely covers only a fraction of affected cases, as many more are still under review, and FBI examiners trained hundreds of state and local crime lab analysts in the same flawed techniques. (Click here to enlarge image.)


Spencer S. Hsu, FBI admits flaws in hair analy­sis over decades, The Washington Post, April 18, 2015; Image cred­it: Washington Post.

See Innocence and Arbitrariness.