My Post colleague Spencer Hsu has the story of Donald Gates.

A man who served 27 years in prison for a rape and murder he didn’t commit accused D.C. police of framing him, in the first federal civil rights claim for damages involving a wrongful conviction in the District.
All sides agree that Donald E. Gates, 64, is “stone-cold innocent,” as his attorneys put it, of the June 1981 murder of Catherine T. Schilling, a 21-year-old Georgetown University student assaulted and killed in Rock Creek Park after leaving the Watergate office building where she worked as a paralegal. But they disagree about whether police actions violated Gates’s constitutional right to a fair trial.
During a two-week trial, Gates’s allegation that two D.C. police homicide detectives and a lieutenant fabricated and withheld evidence has presented an emotional, legal and financial tangle to jurors, who began deliberations Tuesday.
Over days of testimony about regrets and missed chances, the panel has revisited the trauma of the crime and weighed police liability for Gates’s subsequent conviction while facing the prospect of deciding what value to place on lost decades of freedom. . . .
Although it was not part of this month’s trial, Gates’s innocence triggered investigations that led to exonerations of four additional men in the District who had served up to 30 years for rape or murder since the 1980s based on flawed FBI forensic testimony about hairs.
The FBI in April acknowledged that for more than 20 years before 2000, nearly every member of an elite FBI forensic unit overreached by testifying to the near-certainty of hair matches without a scientific basis. Defendants are now being notified.
However beneficial Gates’s exoneration has been to others, he would not have been prosecuted if not for the police informer’s account, according to testimony last week from the original prosecutor, J. Brooks Harrington.

That informant was paid $1,300 for his testimony.

The case is as good an illustration as any that most fields of forensic “science” weren’t developed to find the truth but to aide police and prosecutors in convicting the person they already believe committed the crime. They aren’t neutral methods of analysis; they’re tools for the state. That doesn’t mean some fields don’t have some evidentiary value (though hair fiber analysis has very little). It just means that those that have some value should be considered and presented to juries for what they are. Too often, they’re presented as magical guilt/innocence divining rods.