Ever since Marc-André Grenon was arrested for Guylaine Potvin’s murder, everyone has been wondering what the police could have led to this person 22 years after the tragedy. The court has agreed to release certain elements of the evidence, showing in particular how a new DNA system made it possible to pin him.
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It’s a new technology called genealogical genetics that has allowed Sûreté du Québec investigators to target Marc-André Grenon as a suspect of priority interest.
“Today, the speed of computers has advanced. We’ve been able to identify sequences that match people’s genes with the way their bodies look and a bunch of other things. And we even managed, and we discover that in this file, to establish that the sequence that you find in your DNA is specific, for example, to the Dumonts, the Ferlands, or to this and that surname, because that became The Gene transmitted from father to son,” explained Roger Ferland, ex-investigator at SPVQ, and spoke of the new genetic technologies that were used to solve the “cold cases”.
This is the Y chromosome, which can now be isolated in a DNA sample. The latter is then compared in a public genealogical database and makes it possible to obtain surnames from the same line.
“What’s new is that we’re skipping generations to achieve a level of kinship between the original and what you have as evidence. It will be interesting to watch and how effective it can be,” said Me Charles Cantin, criminal justice attorney.
However, the technology has its limits.
“It only works if you reduce the suspect population significantly enough, otherwise you risk having a lot of ‘matches’. The admissibility of evidence will naturally relate to the issue of constituting databases from various open sources. Especially since the official databases against which we compare such data are subject to a strict legal framework,” explains Frank Crispino, co-director of the Forensic Research Laboratory at the University of Quebec at Trois-Rivières (UQTR).
“We know that DNA has revolutionized the legal system tremendously as we are increasingly able to use this information to track down criminals,” admitted criminal defense attorney Me Luc Tourangeau.
This practice could be presented as evidence in the trial against Marc-André Grenon, which is scheduled to take place next autumn. These new methods could unlock cases that haven’t been solved in years.
“We are inevitably moving towards scientific advances, which means that crime-solving rates should improve,” Me Cantin said.