Young Guylaine Potvin died of strangulation, the forensic pathologist confirmed Tuesday at the criminal trial of Marc-André Grenon, accused of her rape and murder.
The 19-year-old student was found dead in her apartment in Jonquière, now a district of Saguenay, on April 28, 2000.
His alleged killer was arrested in October 2022, more than 20 years after his death. Sûreté du Québec investigators claimed to have been able to identify him using “new investigative methods in forensic biology.” »
On the first day of the trial, on January 15, we learned that the DNA found at the crime scene was finally able to be linked to the accused after the investigation file had been integrated into the PatronYme project. This is based on biology: the Y chromosome – only men have one – is transmitted from father to son. The laboratory’s database therefore raised lines of inquiry, and the surname “Grenon” quickly found itself on the list of “priority surnames”. The investigation then focused on Marc-André Grenon and police surveillance made it possible to recover DNA on straws that he had used, argued the Crown prosecutor, Me Pierre-Alexandre Bernard, when he summarized the evidence that he was going to present to the jury during the trial which is taking place at the Chicoutimi courthouse.
On Tuesday, forensic pathologist Caroline Tanguay explained all the steps that were taken 24 years ago to recover DNA from the victim’s body.
However, she was not the one who performed the autopsy at the time. Dr. Claude Potel, however, took notes and photographs, which were used in Dr. Tanguay’s testimony.
She described to the jury Tuesday that the young woman was killed by a combination of manual strangulation and ligature. A leather belt was found near the body of the young victim, who also had injuries to the genital area.
The toxicology analysis showed an absence of drugs and alcohol in her system, which was consistent with the testimony of her friend with whom she had spent her last evening. Audrey St-Pierre told the jury that she had spent the day working with her on a big school project to be submitted the next day to the Jonquière CEGEP. The two friends had dinner at the restaurant without drinking alcohol and left around 9:30 p.m. to go to bed early, she testified.
If DNA was found in the student’s room, no fingerprints of the accused, Marc-André Grenon, were taken there. Those that were found there – partial prints – did not allow them to be linked to anyone.
A “lack of correspondence” does not amount to an exclusion of the person being compared, however, warned Judge François Huot of the Superior Court who is presiding over the trial. This does not exclude that the targeted person was on the scene, he continued.