Accused killer asked cops: is it like CSI?

A tradesman accused of killing a Sydney woman in her waterfront home lied to police about being inside the mansion the day she died, but backtracked after asking questions about autopsies and the TV show CSI, a court has heard.

Guildford man Tony Halloun has pleaded not guilty to murdering 65-year-old Shahnaz Qidwai in the Henley property she shared with her husband on June 15, 2012.

The NSW Supreme Court trial has heard he gave police three accounts of the day Mrs Qidwai died, including that masked intruders stormed the lavish house where he had been working.

Halloun has now told the jury he made up that story.

But he has also agreed that in his first police interview, he wrongly said he had not been inside Mrs Qidwai's house the day her body was found.

"I was a suspect, a witness in a murder case, so I lied," Halloun said on Wednesday.

Crown prosecutor Giles Tabuteau said Halloun had texted a workmate from the police station on June 15, urging him not to answer any phone calls until the pair had spoken, and telling him: "I didn't go in the doctor's house."

"It was a race against time, wasn't it, for you to get to (the workmate) first before the police did," Mr Tabuteau said.

Halloun subsequently used his wife's phone to urge the man to delete his text messages, Mr Tabuteau said.

Prosecutors say Halloun came clean to police about being inside the Qidwai house only after realising forensic evidence might place him at the scene, or detectives might have already seen his text to the workmate.

The court heard Halloun also asked police how DNA worked and whether fingerprints were still used to solve crimes.

"You said to (one of the detectives), 'Can an autopsy confirm the cause of death?' and he said most often that it can," Mr Tabuteau said.

"And you said, 'Can you get the time of death down to the very minute?' ... It was playing on your mind wasn't it, this question of the time of death."

"No, not at all," Halloun replied.

"I asked, 'Was it just like in the movies, like in CSI?' It was just a general question."

Two days after Mrs Qidwai was killed, Halloun went to Bankstown police station to speak to investigators again and spoke with his workmate in the waiting room.

Mr Tabuteau said microphones in the room recorded Halloun whispering: "About the phone thing, just say I send messages when I go to the toilet."

The prosecutor said Halloun had been trying to convince his workmate to explain away his initial text message, and tell investigators "it wasn't unusual for you to send messages about your - about what happens when you go to the toilet".

The trial continues.