Alleged killer changed story, court told

A man who admits witnessing a woman's murder at a drug-fuelled party and helping bury her body initially told police she was alive when he last saw her.

Micheal John Duffy has pleaded not guilty to the strangulation murder of Colleen Deborah Ayers, whose body was found in a shallow grave in May 2012 at her parents' property in Picton, southwest of Sydney.

He admits he was present when his former lover, Rachael Evans, strangled Ms Ayers with a belt during a sexual encounter but denies joining in.

But less than a month after the killing, Duffy told detectives Ms Ayers was alive when he left the party, his trial has heard.

During a recorded interview with police played at his Supreme Court trial on Thursday, detectives asked Duffy if Ms Ayers was unconscious at any time.

"Not at any time I was there," he replied on June 1, 2012.

Asked if he had any involvement in her death, he replied "none whatsoever".

During the interview, Duffy admitted having sex with Ms Ayers six or seven times in the two days he knew her, including three times on the night she died.

He said they had gone to Ms Ayers parents' property on May 9 and had been drinking and taking drugs.

Duffy then told police he left the party in the early hours of May 10 after Evans disclosed her plan to ransack the house.

"I didn't want any part of it," Duffy said in the interview, "I wanted to get home".

The court earlier heard Duffy and Evans only met Ms Ayers the day before, on May 8, 2012, at a pub in Campbelltown.

By that night the trio were sharing a bed at a Picton hotel while being filmed by a teenager, who cannot be named.

The next day Ms Ayers invited them to her parents' vacant property.

The Crown alleges Evans became agitated when she heard Duffy and Ms Ayers having sex and so she grabbed a belt, repeated the words "I'm going to do it," and then marched into the bedroom and began strangling Ms Ayers.

Evans, who claims Duffy joined in, has already pleaded guilty to the murder.

The trial continues.