A jury has found Marc-André Grenon guilty of first-degree murder in the 2000 death of Quebec junior college student Guylaine Potvin.
Grenon, who was arrested in 2022 after DNA on his discarded drinking straws matched evidence from the crime scene, was also found guilty of sexually assaulting the 19-year-old Potvin.
The verdicts were reached less than three hours after the jury began deliberations Tuesday at the courthouse in Saguenay, Que. Spectators in the packed courtroom could be seen hugging and wiping away tears after the verdicts were read.
Police had honed in on the suspect more than 22 years after the crime when a project tracking Y chromosomes — which are passed down from father to son — suggested the DNA left by the killer was connected to the last name Grenon.
Grenon’s lawyers had admitted he killed the teenager with a brown belt that was found next to her body but argued her death was a burglary gone wrong. Crown prosecutor Pierre-Alexandre Bernard maintained Grenon, 49, strangled Potvin during a sexually motivated assault that began after he spotted her asleep in her bed — making her death a first-degree murder.
Potvin, 19, lived with two female roommates, also students, who were not home when the killing took place inside their Panet Street residence in Jonquière, now a borough of Saguenay, about 215 kilometres north of Quebec City.
Her body was discovered the morning of April 28, 2000. A pathologist testified that the teenager had died of strangulation, with injuries that included blunt trauma to her head and shoulder, a bite mark on her left breast, and injuries to her genital area.
While male DNA was discovered at the crime scene, the trial heard there was no match in the police database and no witnesses to the crime.
Police arrested Grenon in 2022 after following him to a movie theatre and collecting his discarded straws. DNA on the straws were found to match the DNA from the crime scene, including under Potvin’s fingernails, on a T-shirt she was wearing and on a box of condoms found at the scene.
That match was confirmed when investigators obtained a warrant for a second DNA test after Grenon’s arrest.
Crown prosecutor Pierre-Alexandre Bernard argued that Grenon likely saw Potvin sleeping in her bed and decided to sexually assault her.
Because she was killed during a sexual assault, he told the jury, the verdict should be first-degree murder.
The defence argued Grenon had killed Potvin in a struggle after breaking into the apartment to commit robbery, and that any sexual contact took place after the victim had died. Defence lawyer Karine Poliquin suggested a second-degree murder conviction.
Grenon did not testify during the trial, and his lawyer did not call any other witnesses.
The Criminal Code defines first-degree murder as “planned and deliberate,” however a murder is also first-degree if it occurs in the course of a sexual assault.
First-degree and second-degree murder come with automatic life sentences, but with first-degree murder there is no possibility of parole for 25 years. With second-degree murder, parole eligibility can be set at as little as 10 years.
During his final instructions to the jury, Superior Court Justice François Huot said that, contrary to what the defence argued, it was not necessary to prove the sexual assault took place before the death, but only that an assault or attempted assault occurred in the same sequence of events as the killing.
The jury did not hear that Grenon, of Granby, Que., east of Montreal, is also charged with attempted murder and sexual assault in connection with a case in the provincial capital just months after Potvin’s killing.
Police said their investigation into Potvin’s murder turned up similarities with the Quebec City case from July 2000, in which a female student, living alone, was assaulted and left for dead but survived the attack.
Grenon’s arrest was the first made by the provincial police’s cold case squad since it was beefed up with more resources in 2018.
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