The dark side of DNA evidence

Contaminated samples, inept analysts and genetic quirks have led to miscarriages of justice, Kirk Makin reports

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."

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."

Last year, University of Virginia law professor Brandon Garrett and Peter Neufeld, co-founder of the Innocence Project, found that three of 156 U.S. individuals ultimately exonerated in serious crimes had been wrongly convicted because of DNA errors. In one case, a technician grossly overstated evidence. Another featured lab contamination. The third wrongful conviction came after senior analyst Fred Zain gave evidence in court he knew to be false.

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 Texas. His errors became one of several problems the state ultimately faced. "They have had to reopen hundreds of cases in Texas because of the discovery of horrible preservation and contamination issues," said Alan Young, a professor at York University's Osgoode Hall Law School. "They had to literally shut down a lab in Houston because it was generating so many false results."

In other cases, the errors were inadvertent but no less damaging. Several years ago, a developmentally handicapped girl in Australia was linked to the murder of a toddler hundreds of kilometres away based on DNA found on the victim's clothing. It turned out the suspect had recently reported being sexually assaulted. A condom connected with the assault was being tested in a forensic lab at the same time as the murdered child's clothing.

And in England, bartender Peter Hamkin, 23, spent 20 days fearing deportation to face murder charges in Italy in 2002 before Interpol discovered that it had blundered in matching his DNA profile to that of a wanted killer in Tuscany. "I was a prisoner in my own home, constantly on the edge thinking the Italian police were going to arrive to take me away," he said afterward.

Faked results

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.

In Canada, the RCMP, Ontario's Centre of Forensic Sciences and a handful of private labs analyze crime-scene DNA. While CFS has raised its standards since 1995, when an inquiry into the wrongful murder conviction of Guy Paul Morin heard that clothing fibres used to convict him had actually been shed by a lab technician's sweater, an incident last summer was a sobering reminder.

With his first-degree murder trial just two weeks away, Michael Smith of St. Thomas, Ont., learned from the Centre of Forensic Sciences that a defective lot of semen-testing kits several months earlier had yielded a false positive result in his case. "I was shocked that it was a mistake, but also that it had taken so long for them to tell us," said Mr. Smith's lawyer, Robert Upsdell. 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 Toronto lawyer who specializes in DNA cases, said most lawyers simply don't believe they can beat a DNA case and seek a plea bargain. "I would say that 99 times out of a hundred, nobody is fighting it any more," he said. "I suspect that there are lawyers whose clients say: 'Hey, it wasn't me,' and the lawyer says: 'You're going to go down, so let's work something out.' "

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 Toronto lawyer who issues a monthly DNA newsletter, said he was jolted last summer when an Israeli company, Nucleix Ltd., announced it could synthesize DNA. The news raised the spectre of criminals framing innocent people starting with a couple of microscopic cells. "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 professor at Nova Southeastern University, said in a recent scholarly article a chimera can potentially leave misleading DNA deposits at a crime scene. "If he is a chimera, the DNA from his saliva could, in theory, differ from the DNA in his semen, skin, blood or some other sample left at the scene."

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."

Original report here



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