A two-decade investigation. Hundreds of targeted “topics”. DNA checks in dozens of countries. Unprecedented investigative techniques made it possible last year to arrest Marc-André Grenon for the sordid murder of Guylaine Potvin, committed in Jonquière in 2000.
Posted at 4:12pm
Court documents filed during the police investigation and released Thursday after the intervention of certain media outlets, including La Presse, partially lift the veil on this affair that had shocked Quebec. However, dozens of pages of these investigator affidavits remain redacted or banned from publication.
Investigators refuse to reveal certain information in order to protect the identity of third parties, not to jeopardize investigative methods, and even not to endanger the lives of police officers.
Marc-André Grenon, from Granby, was charged last October with the first-degree murder of Guylaine Potvin, a CEGEP student who was raped and strangled in April 2000 at her home in Jonquière.
The 48-year-old man is also accused of sexually assaulting and attempting to kill a student at Laval University in Sainte-Foy in July 2020. The 20-year-old woman was strangled by her attacker and left to die. His identity is protected by the court.
This arrest was the culmination of a long-running investigation by the Sûreté du Québec. From the start, investigators knew the attacker was the same in both files because the same man’s DNA had been found at the crime scene. Not to mention the modus operandi and profiles of similar victims.
The attacker’s genetic profile was therefore the cornerstone of this study. Who did this DNA belong to? A question that remained unanswered for two decades.
During the investigation, no fewer than 339 “targets” were eliminated thanks to their DNA. Only six “subjects” refused to provide their DNA, Sûreté du Québec Sergeant Investigator Michael Gauthier said in an affidavit.
In 2021, an investigator even stepped up his search internationally in hopes of finding the killer. He therefore called for screening of the DNA banks of a dozen American states and thirty countries around the world, from France to Botswana. The police had already made a request to Interpol in 2007.
However, we cannot provide any information on the specific elements that enabled investigators to arrest Marc-André Grenon.
Court documents indicate personal belongings were stolen from Guylaine Potvin’s room. The suspect left with the young woman’s graduation ring, a camera, a small brown purse and the sum of $200 in a red chest.
The police had staged a television program in hopes of relaunching the stalled investigation and gaining additional information. Their goal was “achieved” after the airing of a TVA program in 2005, says a sergeant from Surete du Québec in a request for a production contract.
We also learn, in an affidavit from an investigator, that Marc-André Grenon was arrested just three days before the murder of Guylaine Potvin in a robbery case in Chicoutimi. As an address, he then gave a dormitory for the homeless, which was 18 km away from the young woman’s apartment.
At the time of the crime, Marc-André Grenon already had a criminal record. He had a criminal history of theft, trespassing at night, attempted break-ins, threats and assault. The majority of these crimes took place on the territory of the city of Saguenay, in Chicoutimi and Jonquière, the court document specifies.