When Peter Sgromo decided to enrol in martial arts training a couple of years ago, he had no way of knowing just how valuable those skills would prove to be — until, he says, he wound up in the back of a van with accused serial killer Bruce McArthur.

Sgromo had known McArthur for more than a decade when a casual meet-up with the acquaintance turned into a terrifying encounter that ended shortly after the 66-year-old grabbed and twisted his neck without warning, he told CBC News.

"I think about that grip," Sgromo said. "For him to grab my neck with one hand, twist it like that, I literally thought one more second he would have snapped [it]."

Sgromo had recently moved back to Thunder Bay from San Francisco. McArthur, he said, reached out on a social app called Bear411, suggesting they meet the next time Sgromo was in Toronto.

Met through support group for gay fathers

That was last spring, almost a year before McArthur, 66, would be charged with first-degree murder in the disappearances of five men. None of those charges have been proven in court.

Peter Sgromo had known McArthur for more than a decade when he says a casual meet-up with him turned into a terrifying encounter that ended shortly after, he says, the 66-year-old grabbed and twisted his neck without warning. (CBC) McArthur, said Sgromo, was someone he'd run into from time to time. The pair had met through a former partner Sgromo had dated in the 90s, who was a member of a support group for gay fathers who had come out late in life.

That spring, McArthur seemed adamant to meet, and Sgromo accepted, suggesting they do so at O'Gradys Restaurant in the Church and Wellesley area, where he'd planned to meet another friend. The tone was light and casual, Sgromo recalled, the conversation spanned business and travel, McArthur recounting his recent trip to Italy.

"We had no exchange about anything that would suggest that we were going on a sexual date or anything like that."

But one detail came as a bit of a surprise to Sgromo.

"One odd thing was that he had mentioned that he had met this guy in Italy, and I guess he was talking about the date he was on and he said, 'Oh, he liked it really rough.'"

Van was 'emptied out'

It wasn't a danger sign, but it "came out of left field" to Sgromo, who said he never imagined rough play was McArthur's taste.

"I would imagine getting together with Bruce and cooking a lasagna or making a big pizza, maybe eating it all and drinking a bottle of wine and laughing about it," he said.

Bruce McArthur, of Toronto, is shown in this Facebook image. The 66-year-old man is charged in connection with five Toronto men presumed dead. (Facebook/Canadian Press) As the evening wound down, Sgromo said, he walked McArthur to his van, giving him a hug and a peck goodbye. Instead of parting ways, the pair started to kiss consensually and McArthur offered to drive Sgromo back to his hotel.

When they got into the van, Sgromo said he noticed it was "emptied out."

"Oh, OK, he transports things, so that makes sense," he said to himself, remembering McArthur was a landscaper.

Inside, McArthur went and sat on the bench at the back of the van, and motioned for Sgromo to join him. He did.

"We were kissing, kissing turned into some petting. Then he undid my shirt, undid his shirt," he said, recalling McArthur then grabbing him by the head, pushing him down.

'That's when I really was quite disturbed'

Sgromo wasn't ready for oral sex, he said, so he rose back up.

"Then he really grabbed my neck, violently twisted it, right to his crotch and his pants were undone. That's when I really was quite disturbed."

Bruce, what are you doing? - Peter Sgromo, on what he told McArthur that night

Sgromo said he acted on instinct, grabbing McArthur's elbow by the funny bone until he was able to make it release.

"Bruce, what are you doing?" he said.

The whole encounter seemed out of step with the man Sgromo thought McArthur to be, especially having confided in him some of a few violent encounters he'd had in San Francisco that prompted him to enrol in self-defence classes in the first place.

"He had been sniffing poppers, which is something that a lot of gay men use, but I don't think that made him violent. It was just odd." McArthur, he said, didn't even seem aroused by the action.

The now-66-year-old suggested they go back to his place, but Sgromo said he wanted to check on his sick dog back at the hotel first. When he got upstairs, he said, he texted him saying his dog was too sick for him to leave.

'My gut was right'

"And to me, that was my escape," he said. He never heard from McArthur again.

Sgromo said he assumed McArthur was simply into rough sex and didn't go to police. Now seeing his face plastered across media reports, he said he's grateful he trusted his gut in that moment.

A source, who the CBC has agreed not to name, said Sgromo told him about the alleged incident shortly after it happened and repeated it again once news of McArthur's arrest broke.

But he does have questions about whether police acted quickly enough to arrest him.

Amid growing fears about a possible serial killer in the Gay Village late last year, Toronto's police chief announced there was simply no evidence to support that conclusion.

Bruce McArthur, 66, has been charged with five counts of first-degree murder in the deaths of Selim Esen, 44, Andrew Kinsman 49, Majeed Kayhan, 58, Soroush Mahmudi, 50, and Dean Lisowick, 47. (Toronto Police Service) Investigators have since found the remains of at least three people in two planters they've extracted in their search of some 30 properties connected with McArthur in and around Toronto — extending as far as Peel, York and Durham regions.

Digging is set to begin at one of those properties as early as this week and investigators have said more charges are expected.

Former forensic investigator with York Regional Police, Kevin Bryan, said the plan will be to find "as many human remains as they can," before using forensic techniques to piece the bodies back together, determine how many there may be, and then work to figure out the cause of death.

"They may not know who they're looking for," Bryan said. "There may be missing persons out there that have not been reported yet."