Wednesday, April 22, 2015

"In other words, microscopic analysis of virtually worthless as a method of identifying someone."

Thirty Years in Jail for a Single Hair: the FBI's 'Mass Disaster' of False Conviction

A ‘dirty bomb’ of pseudo-science wrapped up nearly 268 cases – perhaps hundreds more. Now begins the ‘herculean effort to right the wrongs’

By Ed Pilkington

George Perrot has spent almost 30 years in prison thanks to a single hair. It was discovered by an FBI agent on the bedsheet of a 78-year-old woman who had been raped by a burglar in her home in Springfield, Massachusetts, in 1985.

Perrot, then 17, was put on trial, despite the absence of physical evidence tying him to the crime scene. There was no semen. There was no blood. And so there was no way to conduct a conclusive DNA test.

Even the victim testified that the defendant looked nothing like her attacker: he had a short haircut and was clean-shaven, while Perrot had a long shaggy mop, a moustache and a goatee beard.

But there was that strand of hair. At a key stage in the 1992 rape and burglary trial, an FBI agent named Wayne Oakes took the witness stand, describing himself to the jury as an expert in hair and textile fibers – as would so many of the agency’s trial witnesses, in condemning hundreds of people to long prison sentences.

Individual head or pubic hairs were distinctive, he told the court, to the extent that a well-trained specialist like himself could tell those belonging to one person from another. Oakes went on to bombard the jury with scientific jargon, referring to the medulla, the cortex and the cuticle of hair, likening the task of comparing individual strands to recognizing a specific person in a crowd.

“In 10 years, it’s extremely rare I will have known hair samples from two different people I can’t tell apart,” the self-proclaimed expert bragged.

The FBI agent’s conclusion in front of the jury was emphatic: “The hair found on the sheet exhibits all the same microscopic hair arranged in the same way as the characteristics present in the known hair from [Perrot]. I conclude that the hair was consistent with coming from the defendant,” he told the court.

That testimony, based on a single hair, was so strong, so wrapped in the certainties of science, that it wiped out all doubts and inconsistencies in the prosecution’s case – indeed, it eviscerated the presumption of innocence.

There was only one problem: the “expert” analysis, delivered by Wayne Oakes under oath and effective enough to obliterate one-third of a man’s life and counting, was wrong.

‘Potentially tens of thousands’ of cases gone wrong

In July 2013, the FBI admitted that the foundations of what it called “hair comparison evidence” – a technique that its agents had used in hundreds of criminal cases nationwide and spread through the training of state-based detectives potentially through tens of thousands of other cases – were scientifically invalid. A preliminary review of the FBI’s follicular flaws found that:
•Microscopic hair analysis could not scientifically distinguish one individual to the exclusion of all others.
•Statistical weight could not be given to comparisons to suggest a likelihood that the hair derived from a specific source.
•Expert witnesses should not cite the number of hair analyses they had conducted in the lab to bolster the idea that they could definitively state that a hair belonged to a specific individual.

All three errors were made by Agent Oakes in front of Perrot’s jury.

Over the past few years, advanced understanding in the science of hair types has left hair analysis, as a forensic tool, in tatters. Today’s consensus by real experts is more straightforward than ever: there is nothing that can credibly be said, by FBI-approved analysts or anyone else, about about the frequency with which particular characteristics of hair are distributed in the human population.

In other words, microscopic analysis of hair – the very analysis that put George Perrot and so many people behind bars – is virtually worthless as a method of identifying someone. It can only safely be used to rule out a suspect as the source of crime-scene materials or in combination with the vastly more accurate technique of DNA testing.

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