The former senior constable, testifying in his double murder trial for a seventh day, was also lashed by a prosecutor after saying he would have arranged stolen vehicles if he had planned to murder ex-partner Jesse Baird.
"No one's saying (your plan) was a good plan, that's why we're sitting here," crown prosecutor Brett Hatfield SC told the former officer during cross-examination.
Lamarre-Condon, 31, has pleaded not guilty in the NSW Supreme Court to murdering Mr Baird and the TV presenter's new partner Luke Davies with his police-issue pistol at a Sydney terrace in February 2024.
He says his actions in early 2024 were consistent with him contemplating taking his own life due to work-related trauma.
"You were planning the murder of Jesse Baird throughout this period?" Mr Hatfield asked.
"I was 100 per cent not planning the murder of Jesse Baird," Lamarre-Condon replied.
The day before the alleged murders, he took mother Coleen Lamarre to get a hire car and drove to their Balmain home sobbing and wailing while suicidal.
CCTV footage from Balmain police station showed Lamarre-Condon returning from a shift and positioning his body behind the door of a gun safe.
He rejected allegations he was faking returning the gun while slipping it into his backpack out of view of the security cameras.
He said he was allowed to take the pistol home and wore it in a plain clothes holster.
Lamarre-Condon planned on using the gun to end his life that night but was persuaded by a friend to go off the police force instead, he told the jury.
Lamarre-Condon and Mr Baird dated from December 2022 until they broke up in April 2023 when the latter could not commit to an exclusive relationship.
The pair started seeing each other in September for two more months.
Mr Baird ceased contact after discovering the then-officer had deleted contacts from his phone and posted fake social media updates.
On Friday, the former officer said he had stolen bullets from the police station in Miranda sometime in January 2024.
He admitted asking colleagues about how the police force could trace mobile phones, certain apps such as Snapchat, and hire cars.
However, he rejected allegations this had anything to do with murder, saying he planned to move into the proactive unit at the time and wanted information about dial-a-dealer drug operations.
In another discussion, he asked a fellow officer if a police car would be sent out if someone rang triple zero reporting gunshots but fireworks had also been let off.
Just over two weeks before the alleged murders, Lamarre-Condon took his pistol into the Royal National Park and test-fired two rounds with a friend.
He denied this had anything to do with an alleged murder.
"I would not use my police-issue firearm for a murder because it is linked directly back to a police officer," he told the court.
"I have the means to get a gun from a youth gang."
Mr Baird and Mr Davies were fatally shot in their Paddington home on February 19, 2024.
Prosecutors alleged Lamarre-Condon was obsessed with Mr Baird despite the couple breaking up, staking out the other man's house for hours before entering the home to murder him.
The 31-year-old claims he disguised himself as an Uber Eats driver to retrieve belongings from Mr Baird's home and has argued self-defence for the killings.
He led police to where their bodies were stuffed in surfboard bags and buried behind a rural monastery when he handed himself in days after the incident.
The trial continues.
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