Mark Edward Grant couldn't be excluded from DNA results, says lab director
Even though sample degraded, at least 2 men contributed, doc gives 1 in 50 million odds
A judge heard testimony from Dr. Amarjit Chahal on Monday as the retrial of Mark Grant, accused of second-degree murder in the the death of Candace Derksen, entered its third week.
Chahal was the lab director at Molecular World, which tested the DNA that eventually led to Grant's arrest in 2007 for the murder of the Winnipeg girl.
Derksen, 13, went missing in November 1984. Her body was found frozen and tied up with twine in a storage shed a few weeks later.
A jury found Grant guilty in 2011 but a new trial was ordered in 2013 after defence lawyers argued that they were not allowed to present evidence that pointed to another possible killer — an unidentified man involved in a similar attack while Grant was in custody.
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Chahal was called to give testimony about the procedures that were followed in providing analysis of the DNA that was found on the twine used to bind Derksen's hands. Chahal's experience with forensic DNA at the time he conducted the reviews was also called into question by the defence.
Chahal said that even though the DNA samples from the twine were degraded, and contained DNA from at least two male contributors, the lab was able to determine that Mark Grant's DNA could not be excluded as a contributor to the sample.
Chahal said that when findings from two different types of DNA tests were factored together, the probability that the DNA could belong to another random person was 1 in 50 million.
The defence questioned Chahal on his experience working with degraded DNA samples, as well as what data he took into account when providing his review to the Crown.
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The judge-only retrial continues Tuesday and Chahal will return to the stand. Court of Queen's Bench Justice Karen Simonsen is presiding over the trial. Brent Davidson and Michael Himmelman are acting for the Crown and Saul Simmonds is representing Grant.
The trial is expected to last until March.