The dark side of DNA

In a world where the average juror gets his or her information about DNA testing from sources like CSI, and thus tends to think it to be infallible, stuff like this is scary:

Gregory Turner feared he was bound for life in prison after an RCMP lab reported odds of 163 trillion to 1 that a tiny amount of DNA on his gold ring could have come from anybody but a 56-year-old woman found murdered in rural Newfoundland.

The only real evidence in a first-degree murder charge against Mr. Turner, the golden sheen of DNA appeared certain to become a silver bullet in the hands of the Crown.

"I told my lawyer, Jerome Kennedy, that there was no way in the world it was true," Mr. Turner recalled in an interview. "He believed me. He said that I was too stupid to commit that crime and leave no evidence."

A lucky hunch by Mr. Kennedy - now Newfoundland's Minister of Health - saved Mr. Turner from a life behind bars. He sought the name and DNA profile of every technician who had worked at the RCMP lab. It turned out that the technician who had tested the ring had also been working on the victim's fingernails a few inches away, creating a strong possibility of contamination.

The technician conceded at Mr. Turner's 2001 trial that she had also contaminated evidence in two previous cases. In another disturbing twist, it emerged that she had mistakenly contaminated Mr. Turner's ring with her own DNA, causing police to waste considerable time on a futile search for a presumed accomplice.

Mr. Turner still has nightmares. "I remember the judge saying that he was denying me bail based on the likelihood I'd be convicted based on a DNA match," he said. "I think DNA can be good, but its only as good as the people who perform it. I spent 27 months in jail for a crime I didn't do."

From the Globe. Among other things, advocates of capital punishment should take note of stuff like this.