The former police officer, 31, has pleaded not guilty to the February 2024 murders of ex-partner Jesse Baird and Mr Baird's new boyfriend, Luke Davies.
The men's bodies were found at a rural property inside surfboard bags.
A friend of the accused, known by pseudonym Elizabeth Kennedy, previously told a NSW Supreme Court trial she unwillingly accompanied the then senior constable on a trip where he unsuccessfully tried to dump the bodies.
However, the former officer says Ms Kennedy was a willing participant and even encouraged him to hide the bodies rather than handing himself in.
On Tuesday, the jury heard an account directly from Lamarre-Condon via a statement he made to police in June 2025, read by prosecutor Brett Hatfield SC.
In the statement, Lamarre-Condon alleged Ms Kennedy repeatedly lied to police about participation in his attempts to sink the bodies in a dam.
"When the bag wouldn't sink ... (Elizabeth) tried to cut multiple holes in the surfboard cover," Lamarre-Condon said in the statement.
"This is where Luke got the knife wounds to his leg."
Ms Kennedy told the court she was left at the outer fence of the property while Lamarre-Condon tried to dispose of the bodies by himself.
Two days after the trip to the farm, Lamarre-Condon alleged Ms Kennedy pleaded with him to not tell police how she helped.
"Please stick to the plan ... pretend I didn't know what happened," Ms Kennedy allegedly asked of the accused.
After receiving a copy of her subsequent statement to police, Lamarre-Condon said he resolved to make sure her alleged cooperation would be known.
"She flat-out lied to the police regarding her involvement," he said in his statement.
"I wanted to do the right thing for the families as they deserve to know the truth too."
It's the first time jurors have heard from Lamarre-Condon, on his own terms.
Jurors on Monday were played a recorded conversation of the accused murderer and a different friend - who cannot be legally named.
That friend wore a covert listening device when visiting Lamarre-Condon in jail in December 2025.
"I just want to be sure you're not wearing a wire," the ex-officer said after asking his friend to lift his shirt.
"You're so paranoid, bro," the friend responded.
The friend has testified that he heard Lamarre-Condon, then 28, confess to the murders hours after Mr Davies and Mr Baird were shot dead in February 2024.
A changing story across seven police statements led defence barrister John Stratton SC to accuse the man of giving false evidence.
"You don't want to damage your prospects about becoming a police officer, do you agree or disagree?" the barrister asked Monday.
"I disagree," the friend replied.
He met Lamarre-Condon at a sushi restaurant the day after the killings, where he suggested disposing of the bodies in a dam was not a good idea.
He also pointed out a skip bin where the then-officer could dispose of clothing and other items but denied knowing these belonged to Mr Baird and Mr Davies.
The Crown alleges Lamarre-Condon killed Mr Baird "execution-style" at close range through a plan borne of a jealous obsession, before shooting Mr Davies to eliminate a witness.
Lamarre-Condon claims he killed the men in self-defence after entering their terrace to retrieve his belongings, including a surfboard.
His offer to plead guilty to Mr Baird's manslaughter has been rejected by prosecutors.
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