The Dark Side of DNA Testing
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
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
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."
In just 20 years, DNA has become a staple of crime-lab analysis, capturing the imagination of scriptwriters and anchoring thousands of criminal convictions. Its record of accuracy is superb - at least, when samples are collected and analyzed under reliable conditions by experts.
But cautionary tales such as Mr. Turner's are starting to pile up. As scientists are able to analyze smaller and smaller portions of DNA, the spectre of DNA evidence being planted at crime scenes becomes a more chilling possibility. There is also an emerging understanding that some individuals may elude detection because they have more than one DNA profile; that lab botch-ups happen with distressing regularity; and that overly dogmatic or underqualified courtroom experts represent a constant danger.
In a legal paper he wrote in 2004, Mr. Kennedy described the case as a blow to the scientific objectivity of the RCMP lab, as well as the credibility of future DNA reports. "In this case, bad science was exposed," he said. "...This case is an example of how untested scientific techniques, human error and bad science could have combined to obtain a conviction for murder."
Prof. Young describes the Zain
case as "a classic example of why you can't simply roll over and play dead
in the face of science." After his shortcomings at the Virginia State
Police Crime Laboratory were discovered, Mr. Zain
left and became head of a medical examiner's lab in
"They have had to reopen hundreds of cases in
In other cases, the errors were inadvertent but no less
damaging. Several years ago, a developmentally handicapped girl in
In a recent publication of the National Association of Criminal Defence Lawyers, lawyer William Thompson deplored the rash of faked and mistaken DNA results.
"Police and prosecutors have demanded DNA tests in an ever-expanding number of cases, putting pressure on labs to keep pace," he said.
With his first-degree murder trial just two weeks away,
Michael Smith of
Mr. Upsdell asked a top Canadian DNA analyst, John Waye - head of the Molecular Diagnostic Genetics Service of the Hamilton Regional Laboratory Medicine Program - to look into the problem. Dr. Waye recalled that "many, many cases" were affected by the faulty testing kits, including some that had already gone to trial.
While CFS was retesting samples in the Smith case, it discovered that the locations on the victim's body where swabs were obtained had been mislabeled when CFS received them in 2007. "Had the retesting not been required, this mistake would never have been discovered," Mr. Upsdell said.
Dr. Waye said Canadian labs are inspected annually by independent auditors and have improved quality control and tracking of sample. Still, tens of thousands of samples flow in and out every year.
"They do a mind-boggling amount of work, and it is really done as an assembly line. You can do your own job absolutely perfectly, but if somebody messes something up before it gets to you, everything you do is messed up, too."
Leo Adler, a
Mr. Adler said the problem with capitulation is that many cases involve experts making subjective conclusions about DNA sources that were mixed together and in different locations at a crime scene. Technicians can be tempted to stretch their conclusions in the belief that they are helping to convict a dangerous criminal, he added: "When a submission goes in to CFS, it goes along with a police theory."
Ricardo Federico, a
"Sharp, brilliant minds are not always on the side of law and order," Mr. Adler said, citing a Saskatchewan man who surgically planted a vial of somebody else's blood in his forearm in an attempt to foil a blood test several years ago "People are always trying to stay one step ahead."
Another scientific development that has caused concern is the discovery of individuals who have two distinct DNA strands in their bodies. Known as chimeras, they have unusual DNA profiles that can come about either because of a blood transfusion or because two embryos merged in their mother's uterus. Estimates of the number of chimeras range from a tiny proportion of the population up to 10 per cent.
Catherine Arcabascio, a law
Mr. Federico criticized Canadian courts for working on a dangerous assumption that DNA tests are accurate, unless the defence can prove otherwise. "The DNA party is over," he said. "It should be the Crown that has an onus to show that testing has been authenticated."
And no matter how careful Canadian labs are, once they send
a DNA profile outside our borders, anything can happen. Under an Interpol
agreement involving 187 countries,
The so-called Phantom of Heilbronn couldn't have been better named. After two years spent scouring the countryside for the presumed serial killer, German police discovered she didn't exist.
The bizarre tale began in 2007, when an individual's DNA profile began to show up at one crime scene after another. Eventually, 40 crimes - including 14 murders - were attributed to the Phantom.
Embarrassed analysts finally discovered that cottons swabs used by police at each crime scene to obtain DNA samples had been accidentally contaminated by a worker at the factory that made them. It was the worker's DNA that kept popping up, effectively linking the crimes.
From Saturday's Globe and Mail Published on Saturday, Mar. 13, 2010 12:00AM EST Last updated on Wednesday, Mar. 17, 2010 2:50AM EDT, http://www.theglobeandmail.com/news/technology/science/the-dark-side-of-dna/article1499631/