In 1980, 17-year-old Santae Tribble was on trial for the murder of a 63-year-old man who was robbed and shot on the front porch of his Washington, D.C., home. There was little evidence in the case, aside from the testimony of a police informant, who said Tribble had admitted to his involvement. Tribble had a strong alibi too, with a number of witnesses all testifying that he was away at his mother’s in Maryland at the time of the murder. The federal prosecutors, however, had one more piece of evidence. At Tribble’s trial, a Federal Bureau of Investigation (FBI) analyst presented a microscopic examination of hairs from the stocking mask the killer had worn and discarded near the crime scene.

The FBI analyst explained that “[o]nly on very rare occasions” had he ever seen hairs of two individuals with the same characteristic. More pointed, he found the hairs with those of Tribble and concluded that “I found that these hairs . . . matched in all microscopic characteristics with the head hair samples submitted to me from Santae Tribble.” In his closing arguments, the prosecutor went further: “There is one chance, perhaps for all we know, in 10 million that it could [be] someone else’s hair.” Tribble was sentenced to 20 years to life, and served a 23-year sentence.

In fact, none of the 13 hairs belonged to Tribble. Nine years after Tribble’s parole in 2003, DNA tests exonerated him. The hairs were not his, but came from three other individuals—and a dog. The “science” behind the FBI’s testimony was so weak, it couldn’t even distinguish human hair from animal hair. The FBI response to this case and the cases of two other men would eventually lead to one of the largest crime lab audits in history.

Brandon L. Garrett, Bad Hair: The Legal Response to Mass Forensic Errors, Litigation 32–36 (May, 2016).