It started out as a casual date, but it could have easily ended in tragedy.

That’s how Peter Sgromo, a 52-year-old part-time professor, described a surprising and dark encounter he had last year with 66-year-old Bruce McArthur — a self-employed Toronto landscaper who has been accused in a series of at least five killings in the Canadian city.

McArthur hid the dismembered remains of at least some of his victims at the bottom of large planters at work sites, according to Toronto police. The investigation continues, and police said the victim count could rise.

“I have no idea how many more there are going to be,” Toronto Detective Sergeant Hank Idsinga said Monday. “We’re investigating some 30 properties. We believe there are more remains at some of these properties that we’re working to recover.”

Back in April 2017 at the time of their date, Sgromo had no idea McArthur would be charged in a series of killings less than a year later.

As Sgromo and McArthur began kissing in the back of McArthur’s van after some drinks in Toronto’s Gay Village in April, the landscaper suddenly — and brutally — grabbed Sgromo’s neck, Sgromo told the Associated Press.

“He was seconds away from snapping it,” Sgromo told AP. “I really thought my neck was going to be snapped the way he twisted it.”

Luckily, Sgromo said, he’d been trained in martial arts — so he grabbed hold of McArthur’s elbow and was able to free himself and leave the van.

“That was my escape,” Sgromo told the CBC. “My gut was right.”

Sgromo didn’t tell police about the violent incident at the time, he told AP, but Sgromo has spoken to police since hearing of McArthur’s arrest.

Sgromo and McArthur had known each other for 10 years before the date, but reconnected in April after McArthur reached out to Sgromo on an app called Bear411, Sgromo told the CBC. They had first met though Sgromo’s former partner, he said, who knew McArthur from a support group for gay dads.

Sgromo told the CBC that the date at O’Gradys Restaurant in the city’s Gay Village didn’t seem out of the ordinary or particularly romantic.

“We had no exchange about anything that would suggest that we were going on a sexual date or anything like that,” Sgromo said.

But after some drinks, McArthur offered to drive Sgromo — who was visiting Toronto from Thunder Bay — back to his hotel. Sgromo accepted, and the pair began to kiss in the van, he told the CBC.

“We were kissing, kissing turned into some petting. Then he undid my shirt, undid his shirt,” Sgromo told the CBC. “Then he really grabbed my neck, violently twisted it, right [down] to his crotch and his pants were undone ... That’s when I really was quite disturbed.”

Sgromo said the violent move seemed out of character.

“I never thought of Bruce as a rough sex guy,” Sgromo told AP. “I thought of him more of a gregarious jolly guy.”

Investigators in Toronto have been shocked by McArthur’s alleged actions as well.

“The city of Toronto has never seen anything like this,” Idsinga, the detective, said at a Monday news conference announcing additional charges against McArthur. “It is unprecedented and draining. He’s an alleged serial killer and he’s taken some steps to cover his tracks.”

Police continue to search through yards and planters belonging to homeowners who hired McArthur to do landscaping over the years, combing them for dismembered remains or other clues.

“He looked all so normal and business-like,” Parker Liddle, who lives near the home where McArthur stored landscaping equipment, told AP.

Liddle said McArthur would frequently bring large planters to the location.

“To know that something as macabre as this was transpiring over the years is pretty astounding,” Liddle said.

Police have said McArthur may have used gay dating apps for older, larger men — such as SilverDaddies and Bear411 — to scout for victims. He was arrested Jan. 18 and charged with two counts of murder, with three more counts of murder added Monday.

“This case is in its infancy,” Edward Royle, a lawyer for McArthur, told AP. “I’m not going to comment.”

McArthur has not yet entered a plea.