Const. Jean-Pierre Brabant says some passersby found the man's body Sunday afternoon in the parking lot of a commercial building at the corner of Saint-Patrick and Hamilton.
"Following the discovery, police officers and ambulance technicians were able to discover the body of a man aged in his 50s. He was unconscious [and] pronounced dead on site," said Brabant.
Brabant said there were signs of violence on the body.
Investigators will conduct an autopsy to determine the exact cause of death.