Barry Paul Cavanagh and Nathan McIvor, both 38, and Sean David O'Keefe, 39, have pleaded not guilty to murdering Jamie Phillips in the witness's home in October 2018.

The 46-year-old's naked body was found the next day dumped in a vacant lot in Glen Alpine near Campbelltown.

The accused killers' NSW Supreme Court trial was told on Monday the home had CCTV cameras at the front and back door and in a lounge room. But any possible footage of the night in question was on memory cards destroyed shortly after Mr Phillips' death.

"You destroyed the memory card to give yourself a free kick to make up whatever story," O'Keefe's lawyer Richard Pontello SC suggested, during cross-examination.

"No," the woman, who cannot be named for legal reasons, replied.

She denied the camera in the lounge room, where drug deals sometimes took place, was more than a dummy device with a blinking red light.

The witness has told the trial the three accused and Mr Phillips were in her shed the night of the death before the group retreated inside a bedroom in her home.

Hearing banging noises, loud thumps, and voices yelling, she tried and failed to enter the locked room but heard Cavanagh say "Shut the f*** up," McIvor say "you want to play games?", and O'Keefe say "be quiet".

She retreated to her room, followed by O'Keefe and McIvor who warned her to remain quiet.

Despite having pleaded guilty to destroying evidence and signed a facts sheet stating she flushed multiple memory cards down a toilet, the woman said on Monday she only destroyed a card connected to the front door camera.

The facts sheet stated the cameras would have "captured all people present in the house, including the accused persons and "the deceased being taken from the house", the trial was told.

"I don't know if the CCTV footage, if it recorded or didn't record. To my knowledge, I thought it recorded off the hard drive," the witness said on Monday

Mr Pontello, whose client has confessed to stabbing Mr Phillips in self-defence, accused the witness of bragging about destroying the evidence.

But the woman said a recording of her saying "they're not going to get anything ... I took them all and f***ing flushed it" was a reference to footage of drug dealers coming to her home.

The Crown argues the accused men acted in a joint criminal enterprise to cause grievous bodily harm to Mr Phillips through a "sustained or prolonged physical assault".

Cavanagh is accused of pulling out the knife that ultimately killed the 46-year-old.

But Mr Pontello argues Cavanagh and McIvor were out of the room when Mr Phillips lunged "without warning" at O'Keefe while armed with a hunting knife.

The witness's cross-examination resumes on Tuesday.

Australian Associated Press