The 31-year-old former senior constable wrapped up a heated cross-examination during his seventh day in a NSW Supreme Court witness box on Friday.
He was grilled about what happened after his estranged lover Jesse Baird and the TV presenter's partner Luke Davies were shot with his police-issue pistol at a Sydney terrace in February 2024.
He has pleaded not guilty to the fledgling couple's murder.
Lamarre-Condon was questioned about his movements after the two men were killed, including putting their bodies into surfboard bags and loading them onto his van.
He made a number of hardware purchases, including cement, a wheelbarrow, tarpaulins, bin liners, a shovel and a chainsaw.
"Was (the chainsaw) to cut up the bodies?" crown prosecutor Brett Hatfield SC asked.
"No, never, no way, not a thought in my mind, never," the 31-year-old replied.
The former officer admitted treating the bodies in a terrible way by trying to submerge them in a dam southwest of Sydney and later burying them behind a monastery.
He was facing a moral dilemma of wanting to hand himself in but fearing what would happen to him as a police officer in jail, the court heard.
After the unsuccessful attempt to sink the bodies, Lamarre-Condon put them back in his van and stopped at McDonald's for a frappe and a chicken burger on the way home.
Lamarre-Condon testified that if he wanted to commit murder, he would have taken a series of different steps including getting a gun from a youth gang and having cleaning products on hand at the time.
He was lashed by Mr Hatfield after saying he would also have arranged stolen vehicles, and not used one linked to his mother.
"No one's saying (your plan) was a good plan, that's why we're sitting here," the prosecutor said.
Lamarre-Condon says he purchased a drill to remove a bullet lodged into one of the terrace's bedroom doors after Mr Davies accidentally shot himself in the head.
Prosecutors have disputed this however, saying Mr Davies was shot through the door because Lamarre-Condon did not want any witnesses.
They claim Mr Baird was earlier shot in the back of the head as he ran away from the jealously obsessive former police officer who then shot him again to execute him on the floor.
The 31-year-old stood by claims he had acted in self-defence when Mr Baird came at him with a knife.
Lamarre-Condon said he was wearing a motorcycle helmet disguised as an Uber Eats driver to retrieve some belongings and his former love interest did not recognise him.
His actions in early 2024 were consistent with him contemplating taking his own life due to work-related trauma, the former officer said.
He planned on using the gun to end his life the night before the fatal incident but was persuaded by a friend to leave the police force instead, the jury heard.
Lamarre-Condon and Mr Baird dated from December 2022 to April 2023, when the latter could not commit to an exclusive relationship.
They started seeing each other again in September for two more months.
Mr Baird ceased contact after discovering the then-officer deleted contacts from his phone and posted fake social media updates.
Lamarre-Condon said he stole bullets from Miranda police station sometime in January 2024.
He admitted asking colleagues about how police could trace phones, mobile apps, and hire cars but said this was connected to investigating dial-a-dealer operations and not any murder plan.
In another discussion, he asked if a police car would be sent out if someone rang triple zero reporting gunshots but fireworks had also been let off.
The accused will be re-examined by his barrister on Monday.
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