Quebec cold case murder: Crown tells jury accused admits he killed teen in 2000

SAGUENAY, Que. — The Quebec man charged with the first-degree murder and sexual assault of 19-year-old junior college student Guylaine Potvin nearly 24 years ago now admits to causing her death, a Crown prosecutor said Wednesday.

Prosecutor Pierre-Alexandre Bernard made the announcement during his closing arguments in the case against Marc-André Grenon.

“The defence will admit that it’s Marc-André Grenon that caused the death of Guylaine Potvin, but by inferences that are different than those we will present to you,” he told the jury at the Saguenay courthouse, some 215 kilometres north of Quebec City.

Grenon’s defence lawyers, who did not call any witnesses, were scheduled to present closing arguments Wednesday afternoon. However, a technical problem meant that there was no video link to follow the afternoon proceedings from outside the courtroom. Bernard had told the jury the defence would argue that Grenon went to Potvin’s apartment with the intent of committing a robbery, and that she died during a struggle.

Grenon, 49, has pleaded not guilty to first-degree murder and sexual assault in connection with the death of Potvin, who was found in her basement apartment in April 2000 in Jonquière, Que., now a part of Saguenay.

His name surfaced in the investigation in 2022 after a DNA research project suggested someone with his last name could be connected to the murder, and he was arrested after DNA from a cup and straws he had discarded matched evidence from the crime scene.

Bernard told the jury that the evidence at the crime scene suggests Grenon sexually assaulted Potvin in her bed as she slept — a place where she should have felt safe — and strangled her with a belt.

“Tragically, Marc-André Grenon literally had the fate of Guylaine Potvin in his hands,” Bernard said. “He took advantage of Guylaine’s great vulnerability to sneak attack and control her and master her to facilitate the perpetration of sexual assault.

“Despite all the strength and determination that Guylaine Potvin could give, Marc-André Grenon succeeded in his project, which was to satisfy his sexual urges, and at all costs, even if the death of the victim was to result.”

The Criminal Code of Canada defines a first-degree murder as one that is “planned and deliberate;” however a murder is also considered first-degree when it is caused while a person is committing or attempting to commit a sexual assault.

Bernard argued to the jury that there is evidence for both scenarios in Grenon’s case.

He referred to the testimony of a crime scene technician, who noted that the victim’s bed was the only place in the apartment that showed signs of a struggle. That, Bernard argued, suggests Grenon entered the apartment and made the decision to assault Potvin while she was sleeping.

He noted that the accused’s DNA was found under Potvin’s fingernails, around her genital area, on a T-shirt she was wearing as well as on a box of condoms and a belt found at the scene, which he said suggest both violence and a sexual element to the crime.

“It is very frequent to find the DNA of the aggressor under a victim’s nails, because when a victim is attacked, they defend themselves,” Bernard said.

The trial has heard that Potvin’s battered, mostly naked body was found on her bed on the morning of April 28, 2000. While male DNA was collected at the scene, there was no match in the criminal database, and no arrest for more than 20 years.

Grenon came under suspicion in 2022 after the DNA found at the scene was entered into a database by the province’s crime lab that analyzes the Y chromosomes of unknown samples and suggests potential surname matches.

After the last name “Grenon” was identified, police tracked the suspect to a movie theatre and seized a cup and drinking straws he had discarded. The DNA taken from the straws was found to match the crime scene DNA, as was a DNA sample taken directly from Grenon after his arrest, the trial has heard.

This report by The Canadian Press was first published Feb. 14, 2024.

— By Morgan Lowrie in Montreal

The Canadian Press