Beau Lamarre-Condon, 31, has pleaded not guilty to murdering ex-partner Jesse Baird and Mr Baird's new boyfriend Luke Davies on February 19, 2024.
A childhood friend of the former senior constable gave evidence on Wednesday about an hours-long road trip south of Sydney two days after the men's deaths.
Known by the pseudonym Elizabeth Kennedy, she said she unwillingly accompanied Lamarre-Condon to Bungonia, during which the senior constable attempted to dump the bodies at a farm.
But Lamarre-Condon's barrister suggested in cross-examination Ms Kennedy willingly participated in the elaborate clean-up.
"Before you got into the white van, you well and truly knew there were two dead bodies in the back," John Stratton SC asked in the NSW Supreme Court trial.
"Wrong," Ms Kennedy said.
Mr Stratton also challenged Ms Kennedy's evidence she never noticed anything out of the ordinary in the back of the van.
He suggested Lamarre-Condon showed her Mr Baird's head before they drove off as she responded "Oh my God, I saw his head, you're not joking".
Ms Kennedy denied the claim.
The former officer's barrister put to Ms Kennedy that she had encouraged the disposal of the bodies.
"Did you say: 'I watch a lot of crime documentaries, we have to hide the bodies, they won't believe you'?" Mr Stratton asked.
"No," Ms Kennedy replied.
Ms Kennedy, who has not been charged over events surrounding the alleged murder, is giving evidence after providing an induced statement to police.
Mr Stratton asked whether Ms Kennedy referenced a famous pop star's song to emphasise the gravity of the officer's situation.
"No, no, no ... they won't believe you, this is like the Taylor Swift song 'No Body, No Crime'," Ms Kennedy was asked if she said to the accused.
But the officer's friend denied bringing up the song, saying it was Lamarre-Condon who raised the music icon.
"He was the one who put that song on in the car ... it's not one of her mainstream songs," Ms Kennedy said.
When they reached Goulburn, Lamarre-Condon made Ms Kennedy buy an angle grinder from Bunnings, she said.
Ms Kennedy said he took a long time to cut the padlock using the angle grinder after arriving at Cella Farm.
She said he then left her at the gate and drove into the property, where he stayed 30 to 40 minutes.
But Mr Stratton said she was lying and Ms Kennedy participated in the failed attempt to sink the bodies in a dam using quick-set concrete.
The defence barrister suggested Ms Kennedy said to the accused: "Just say I waited at the fence line at the farm."
Ms Kennedy denied the suggestion.
Earlier in the NSW Supreme Court trial, jurors were shown extensive CCTV footage of Lamarre-Condon in disguise and later making purchases on the day after the killings.
On the evening of February 20, he picked up a friend, yet to give evidence at trial, and went to a Sushi Train restaurant in Cronulla.
The Crown alleges the friend seen with Lamarre-Condon at Sushi Train is the same person seen on CCTV buying a surfboard bag with the officer three days earlier.
When driving the friend back to his house, the accused's Tesla can be seen stopping at Club Cronulla.
A man, alleged to be the friend, gets out of the passenger side of the car and inspects a skip bin in the car park.
Later that night, the same camera at the bowling club captures a white van pulling into the car park.
A figure lifts the bin lids and dumps items in it.
The bloodied belongings of Mr Baird and Mr Davies were found in the bin by a groundskeeper at the club the following day.
The trial resumes on Friday.
1800 RESPECT (1800 737 732)
Lifeline 13 11 14
Men's Referral Service 1300 766 491
19°C