A Crown attorney accused a Halifax man Tuesday of trying to find a way to blame off-duty police officer Catherine Campbell for her own death.

Cross-examining Christopher Garnier at his murder trial, Christine Driscoll questioned Garnier's claim that Campbell had asked to be slapped and choked, suggesting a different scenario had unfolded.

"There was a struggling on the bed, wasn't there?" Driscoll asked as she cross-examined Christopher Garnier Tuesday at his murder trial.

"No. There wasn't," he replied. "I did not punch Ms. Campbell."

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

In his opening statement Monday, defence lawyer Joel Pink told the 14-member Nova Scotia Supreme Court jury that Campbell died accidentally during "rough sex" that she initiated.

Garnier, 30, told the jury that during sex play, Campbell encouraged him to choke and slap her before she died. But he said his memories about the night are fragmented.

"You've come up with an explanation that explains from your point of view what happened and also entirely places the explanation and the blame on Ms. Campbell, correct?" said Driscoll.

"I'm not trying to blame Catherine ... She was nice to me that night," Garnier said, speaking in a low voice. "Just because she wanted to do that doesn't make her a bad person."

Driscoll focused her cross-examination Tuesday on inconsistencies between what Garnier told police about the night Campbell died and what he told the jury.

She noted he told police after his arrest that he heard Campbell's last breaths, but told the jury he heard air leaving her lungs in the early hours of Sept. 11, 2015.

Garnier said he didn't know at the time of the 9.5-hour-long police interrogation on Sept. 16, 2015, whether he heard gasps or air coming out of her lungs, because he was having a hard time remembering details about the incident.

Driscoll noted Garnier was trained as a firefighter.

"You're a trained first-responder, and you don't know what you heard?" she asked.

"I was trying to decipher what I was hearing. I didn't know," said Garnier, dressed in a black sweater with grey and white stripes across the chest.

She added that as a trained first-responder, he would know that if someone's neck is injured, great care needs to be taken in the handling of that person.

Driscoll said Garnier told the jury his arm was across Campbell's neck, that he went to get a towel when he noticed blood after slapping her, and that he pulled her up by the shoulders and shook her after coming back into the room and seeing her motionless.

"You're not the least bit worried about injuring her?" said Driscoll.

"Honestly, I don't know what I was thinking," he replied.

Driscoll questioned why Garnier did not perform CPR on Campbell or call 911.

She said that during the police interrogation, Garnier told the officers that he had told them what he could remember about the night, and didn't have any reason to hold back.

But Driscoll noted he never told them anything about Campbell mentioning domination, or asking him to choke her. She pointed to the fact that Cpl. Jody Allison asked about rough sex during the interview.

Garnier told the jury Monday he was telling interrogators what they wanted to hear, and that he didn't want them to think "I was just trying to blame it on her."

"Well you're blaming her today, aren't you," Driscoll said on Monday.

Driscoll also suggested it would have been difficult for Garnier -- who is right-handed -- to slap Campbell with his left hand, as he described for the jury on Monday.

Garnier said that slapping her with his left hand was awkward, and that he believes his watch hit her face. Driscoll noted it was the first time Garnier mentioned the watch.

A medical examiner has testified Campbell had facial injuries including a fractured nose.

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

He finished testifying Tuesday. The trial continues Wednesday.