Sex play gone bad?

Christopher Garnier says Catherine Campbell coaxed him into choking her during sex play, and urged him to apply more pressure before she died.

Garnier is on the stand today at his trial in the off-duty police officer's death; his lawyer opened the defence case by telling the jury Campbell died accidentally during rough sex.

Garnier said he met Campbell at a downtown bar in the early hours of Sept. 11, 2015, and they went to his friend's McCully Street apartment.

He told the jury she asked him if he was "into domination," and asked him to slap and choke her.

The Crown alleges Garnier punched and strangled the 36-year-old Truro, N.S., police constable and used a compost bin to dispose of her body near Halifax's Macdonald Bridge.

He has pleaded not guilty to second-degree murder and interfering with a dead body.

Garnier said they decided to go to the McCully Street apartment after kissing at the bar.

They started kissing in the apartment hallway, he said, and "she asked me if I was into domination."

He said he told her didn't want to have sex and she said: "That doesn't mean we can't play."

"She asked me to choke her. I didn't say anything," he said.

"She told me it was OK and not to worry."

He said he put pressure on her neck, but she asked him to squeeze harder. He had both hands on her neck for 30 seconds, he said.

"I don't think I was using very much force," he testified. "If she ever resisted I would have stopped."

They moved to a pullout couch in the den, where she asked him to slap her, he said.

"I did it three times, fast," he testified.

"I was uncomfortable and embarrassed about what I was doing. She kept saying it's OK."

He said his forearm was across her neck, and that he felt his arm getting wet, and saw blood.

He went to get a towel and when he returned, she wasn't moving.

"I shook her a little bit and I could hear air come out of her lungs," Garnier said.

His testimony continues.