Mark Edward Grant couldn't be excluded from DNA results, says lab director

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.

Even though sample degraded, at least 2 men contributed, doc gives 1 in 50 million odds

Holly Caruk CBC News Posted: Jan 30, 2017 6:53 PM EST | Last Updated: January 31, 2017

Mark Edward Grant was convicted in 2011 of second-degree murder in connection with the 1984 death of Candace Derksen, 13. In 2013, the Manitoba Court of Appeal ordered a new trial, ruling the trial judge was wrong to exclude evidence that the defence argued suggests Derksen might have been killed by someone else. (CBC)

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 atMolecular 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 November1984. 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.

Chahalwas called to give testimony about the procedures that were followed in providinganalysis of the DNA that was found on the twine used to bindDerksen'shands.Chahal'sexperience with forensic DNA at the time he conducted the reviews wasalso 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 twodifferent 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.

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.

Timeline of the Candace Derksen case, Winnipeg teen found dead in 1985

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