A joint project by the U.S. Department of Justice, the FBI, the New York-based Innocence Project and the National Association of Criminal Defense Lawyers is re-examining FBI analysts' testimony and findings in thousands of cases involving microscopic hair analysis. The FBI has acknowledged most of its analysts overstated the reliability of the technique more than 90 percent of the time. This is what hair looks like under a microscope. Credit: Courtesy of Microtrace LLC
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Wisconsin, U.S. used flawed hair evidence to convict innocent people

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Alexandra Hall reports on flawed hair analysis on Wisconsin Public Radio

The FBI, the New York-based Innocence Project and the National Association of Criminal Defense Lawyers are examining nearly 3,000 cases nationwide in which the FBI may have misused microscopic hair comparison.

The review so far found statements and findings that “exceeded the limits of the science” in more than 90 percent of the cases. The errors fall into three broad categories:

Claiming a ‘match’

What they did: Examiners stated or implied that the evidentiary hair could be associated with a specific individual to the exclusion of all others.

Why it was wrong: Absent DNA testing, hairs are not unique enough to be associated with one person, even by looking at them under a high-powered microscope.

Claiming a statistical weight

What they did: Examiners assigned a statistical weight, probability or likelihood that the questioned hair originated from a particular source.

Why it was wrong: No such weight can be assigned because no one knows how many people have microscopically identical hair.

Citing experience to bolster findings

What they did: Examiners cited statistics such as the number of hair cases they or the FBI lab had handled to bolster the findings.

Why it was wrong: Unlike DNA, there is no database of hair profiles. Analysts cannot memorize every hair they have ever examined. And comparing vast numbers of hairs — even billions — does not change the fact that an unknown number of people have hair that looks identical.

Sources: National Association of Criminal Defense Lawyers; FBI; Skip Palenik, Microtrace LLC.

Dee J. Hall

Hall, a co-founder of the Wisconsin Center for Investigative Journalism, joined the staff as managing editor in June 2015. She worked at the Wisconsin State Journal for 24 years as an editor and reporter focusing on projects and investigations. Previously she was a reporter for eight years at The Arizona Republic in Phoenix, where she covered city government, schools and the environment. During her 35-year journalism career, Hall has won more than three dozen local, state and national awards for her work, and is a member of Investigative Reporters and Editors. She is based in Madison, Wisconsin. She can be reached at dhall@wisconsinwatch.org