A glass and two straws used by Marc-André Grenon were recovered from the trash can of a cinema.
< p class="StyledBodyHtmlParagraph-sc-48221190-4 hnvfyV">It was only 22 years after the murder that the alleged assassin was arrested in Granby.
In order to relaunch the investigation, Guylaine Potvin's file was added to the PatronYme project. As part of this project, the Montreal Laboratory of Judicial Science and Legal Medicine created the pYste database. The latter contains thousands of public genetic profiles from online genealogy sites.
Men's DNA contains a Y chromosome. This is passed from father to son, so the Y profile of men from the same paternal line is the same. Traditionally, the father's family name is also passed down from one generation to the next.
The unknown DNA in Guylaine Potvin's file was therefore compared to the data contained in pYste. The Grenon surname has been targeted as a surname of priority interest. This is what allowed Sûreté du Québec investigators to relaunch the investigation and find Marc-André Grenon, whose name had appeared in police files a long time ago.
In August 2022, investigators obtained the right to follow Mr. Grenon and they seized, without his knowledge, a cup and straws that he had used in a cinema in Granby. By comparing his DNA and that found in Guylaine Potvin's room, there was a match.
The police thus obtained a warrant and they arrested Marc-André Grenon at his workplace on October 12, 2022.