Improper forensic testimony
Since at least the early 1970s, the FBI Laboratory’s hair and fiber unit trained hundreds of state and local examiners to testify about the rareness of coincidental hair matches, citing their case experience. However, there was no accepted scientific research behind the claim. The FBI stopped declaring matches without DNA confirmation in 1996, but it took until this year for authorities to announce a review, limited to cases involving FBI examiners. Read related article.
Source: Staff reports, FBI International Symposium on Forensic Hair Comparisons. The Washington Post.