Mark Edward Grant is charged with first-degree murder in the 1984 death of 13-year-old Candace Derksen.
A small amount of degraded DNA from 26-year-old evidence that links linking Mark Edward Grant to the 1984 death of Candace Derksen is under attack by the man's defence lawyer.
Amarjit Chahal, the scientist who reviewed the DNA profiles in the case, has already testified there is one-in-50-million chance the evidence found on Derksen's body was not Grant's.
To put that in perspective, you'd have a three or four times better chance of winning a 6/49 jackpot than the DNA being from someone else. But throughout the trial, defence lawyer Saul Simmonds has been questioning the reliability of the DNA evidence in this case, and he continued Tuesday during his cross examination of Chahal.
Simmonds challenged the credibility of the lab which did the tests. Although Molecular World in Thunder Bay, Ont., works with police forces from across Canada, Simmonds noted it has done no independent work on the reliability of results from degraded DNA.
Very small amounts of degraded DNA were obtained from the twine used to bind Derksen, a 13-year-old girl who disappeared on her way home from school at the end of November 1984. Her frozen body was found six weeks later in a brickyard shed.
Simmonds noted that Chahal was unable to find all the markers he was looking for in the sample obtained from the twine. The scientist acknowledged he found only 10 of the 15 markers he was seeking.
"What you don't indicate is that a partial profile is at risk of being incomplete and misleading," Simmonds said.
Chahal did not agree.
"If it was misleading, then we would have guidelines in place that no partial profiles be included," he said, suggesting that rather than being misleading, it meant one had to adjust the probabilities when interpreting the results.
DNA also was obtained from seven hairs isolated from the 100 or more found on Derksen's body using three different tests.
A few years earlier a single test for nuclear DNA the RCMP had conducted on the twine was inconclusive.
Simmonds recounted the long list of police officers and experts who touched all the evidence over the years and did not provide samples of their DNA so it could be excluded from results.
He also questioned why Chahal had looked at Grant's DNA before he looked at the unknown sample and then matched it to Grant.
"Before you look at the final sample that you are going to base everything on, you have already looked at Mr. Grant's sample," Simmonds charged.