A Toronto man is on trial for murdering a hookup he met at a popular cruising ground.

Derrick Lawlor admitted to police he's frequently possessed by the urge to murder other gay men, and that having anonymous sex is the only way to fight it. “I want to kill them. I'm angry like some rage is in me," he told detectives. "It’s getting worse—it’s escalating."

But the 56-year-old pleaded not guilty to the murder of Mark McCreadle, a divorced father of two he encountered in Victoria Park in Kitchener.

According to the Crown, Lawlor came across McCreadie and another man having sex on the night of April 9, 2014, and joined them. After the other man left, Lawlor allegedly strangled McCreadie, 50, and stabbed him several times.

He later called police from Grand River Hospital, telling them he had information about McCreadie’s murder. Officers came to the hospital and arrested him.

During interrogation, Lawlor reported he'd been “violently raped” the year prior, which only fueled his alcoholism and promiscuity. “I became sexually promiscuous after the rape,” he said. “There are times I go into a dark place in my mind. I never hurt anyone that I can remember.”

Authorities interviewed the third man in their encounter—he claimed Lawlor tried to put a scarf around his neck but he pulled it off and left. Lawlor says he remembers wrapping a scarf around a man’s neck, but not much else.

According to friend Randy Scott, Lawlor talked frequently about his desire to punish "offenders." "At one point he commented to me that if he only had two months to live, he would kill every sexual offender."

After losing his job as a student advisor at the University of Waterloo, Lawlor's anxiety and alcoholism only worsened. Once, he admitted, he went home with a businessman and fought the urge to attack him. “I was... trying to convince myself he was a decent guy and not who I thought he was,” he told authorities. “I had the knife with me that night.”

Apparently, he succumbed to his homicidal urges at least once before: In 1985, he was convicted of suffocating a man he shared a cabin with him in Newfoundland. He served just four years for manslaughter.