The Greens were on an interstate holiday when they heard their property, in Lakesland, south of Sydney, had been ransacked.

When they returned in late May 2012, they reported their 33-year-old daughter Colleen Deborah Ayers missing.

The NSW Supreme Court on Wednesday heard that Ms Ayers invited a group of people back to the property on May 9, after a day of using drugs and having a threesome, and she was murdered during a sexual encounter with Micheal John Duffy.

Her body was found buried near a dam on May 31.

The jury has been told they will hear evidence that another woman, Rachael Margaret Evans, burst in on Mr Duffy and Ms Ayers as they had sex in a guest house on the property and started choking her with a leather belt.

Mr Duffy, 34, who has pleaded not guilty to murder, is accused of helping Evans strangle Ms Ayers before they robbed the Greens' house late that night.

The jury has been told that Evans has pleaded guilty to Ms Ayers' murder and will give evidence.

In her opening address, Crown prosecutor Elizabeth Wilkins, SC, said there would be evidence that Ms Ayers met Mr Duffy, Evans and another woman at a pub in Picton, before the group caught a train to Campbelltown and checked in to a hotel for the night.

Mr Duffy, Ms Ayers and Evans had sex, while another woman filmed them, and the group bought drugs to share in a Campbelltown park the next morning, Ms Wilkins said.

That evening the group, including two other men, caught a taxi to the Greens' property, where they lit a bonfire, and started drinking in the guest house.

The jury was told of evidence that Evans became agitated when she could hear Mr Duffy and Ms Ayers having sex, and got a leather belt, saying: "I'm going to do it, I'm going to do it."

"Rachael Evans will tell you that she did go in with a belt and she did put it around the deceased's neck, with the intention of strangling," Ms Wilkins said.

"But I expect she will tell you that the deceased struggled and bucked her off ... and it was at that stage that the accused, Mr Duffy, intervened and also started strangling the deceased."

Ms Wilkins said some of the group washed Ms Ayer's body before burying her, destroying evidence, and robbing the Greens' house.

The same taxi driver who dropped off the group picked them up the next morning, and asked them how their night was.

"[Rachael Evans] said 'Yeah, it was great, very exhilarating,' " Ms Wilkins said.

Defence barrister James Trevallion told the jury it was Evans and a teenage girl, who cannot be identified, who killed Ms Ayers.

"The motive Rachael Evans had, I expect you'll hear, is simply a twisted desire to kill somebody."

Mr Trevallion said Evans and the girl agreed to blame Mr Duffy if they were questioned by police.

"It's the defence case that this is what happened."

Mr Trevallion said there was no issue that Mr Duffy helped bury the body, and stole some items from the Greens' house.

The trial continues before Justice David Davies.