Brian Casement, shown outside court in Saskatoon on Friday, testified in his own defence. ((Dan Zakreski/CBC))

A man accused of killing a Saskatoon woman claims her death was an accident that stemmed from a violent sex act.

Brian Robert Casement, 60, told a jury on Friday that he was having sex with Victoria Jane Nashacappo, 21, after having picked her up on the streets of Saskatoon in September 2002. Nashacappo, the defence claims, was a prostitute.

In graphic language, Casement testified that the sex act became violent at Nashacappo's request. He said she asked him to choke her.

"I asked her if she was all right," Casement said, claiming that she answered with an emphatic, "Yes, don't stop."

Casement went on to describe the sex act in detail. When it ended he said he got up, got dressed and then noticed "she was still lying there."

He testified that he tried to revive the victim using CPR, without success.

Casement's lawyer, Daryl Labach, then asked his client directly about the victim's death.

"Did you murder Victoria Nashacappo?"

"No, I did not," Casement replied.

It was a far different story than that presented to the jury earlier in the trial by the Crown prosecutor.

Much of the Crown's evidence against Casement centred on admissions, captured on videotape by undercover police, that he killed the woman because — as he was heard on videotape to say — "Dead people don't talk."

Jurors have been told that undercover officers spent months pretending to be members of a mob family, hoping to induce Casement into revealing information about his connections to an unsolved murder.

The role-playing culminated in a dinner meeting aboard a yacht in Vancouver harbour, where Casement was secretly taped making a number of admissions to the supposed leader of the gang.

But Labach, in opening the defence case on Friday,  urged jurors to keep an open mind about what they saw.

'You 12 people need to know what really happened.' —Daryl Labach, defense lawyer for Brian Casement

"It becomes too easy to say, 'He did it. Why are we here?'" Labach said as he began the defence's case.

"Hear Brian out," Labach said. "You 12 people need to know what really happened."

Casement's testimony began with a description of a life of crime and drug addiction. He appeared pale as he calmly answered his lawyer's questions.

The elaborate police deception that led to Casement being charged continued to dominate the case. However, Casement presented himself as someone who would have said anything to impress the supposed mobsters.

He offered an example of how he hoped to enhance his reputation, saying he had evidence that the mob might find useful.

"If you ever need it, I've a picture of a Supreme Court justice in his chamber with a hooker," Casement claimed he told an undercover officer.

"Was that true?" his lawyer asked.

"No, it was a lie," Casement replied.