Marc-André Grenon, accused of the murder of Guylaine Potvin, was identified more than 25 years after the homicide by his Y chromosome and two straws, the Crown intends to demonstrate during the trial.
The 19-year-old student was found dead by a friend in her apartment in Jonquière in April 2000. Her undressed body showed signs of violence.
There were no witnesses. No one heard anything that night, Crown prosecutor M.e Pierre-Alexandre Bernard, in his preliminary presentation offered to the 14 members of the jury.
DNA was collected from the crime scene, but DNA alone is not enough to identify a suspect if there is not a sample to compare it to, M summed up.e Bernard.
“The mystery remains. »
In short, for many years, the police investigation failed to identify a suspect and the murder remained on the list of unsolved homicides.
Then, in October 2022, a major turnaround occurred: a suspect, Marc-André Grenon, was arrested by investigators from the Disappearances and Unresolved Files Division of the Sûreté du Québec (SQ). The police had mentioned the use of “new investigative methods in forensic biology”, without giving further details.
We turned to science, revealed Tuesday Me Bernard. “Science sometimes allows us to see where the eye is blind. »
He explained how he intends to prove that Grenon is indeed the author of the alleged crimes.
There was talk of the “PatronYme” project, which is based on biology: the Y chromosome is transmitted from father to son, explained the prosecutor, and in the West, the surname given to a child is generally that of the father.
Thus, the police investigation is directed towards the Grenon family name, then, in June 2022, it is directed more specifically towards Marc-André Grenon. Police surveillance allowed the recovery of two straws and a cup that the accused used and which he got rid of.
The DNA on the two straws matched DNA taken from the crime scene, M continued.e Bernard. Grenon is then arrested. The man, now 49, has been charged with aggravated sexual assault and first-degree murder.
Monday morning, in the crowded courtroom, he pleaded “not guilty” in a weak voice to the two charges against him.
None of the facts alleged by the Crown prosecutor have yet been proven. But he will call 11 witnesses and present numerous evidence to the jury in order to convince it to find the accused guilty. The latter, however, is presumed innocent until proven guilty. The trial is expected to last five weeks.