The 31-year-old has pleaded not guilty to the 2024 murder of Network Ten presenter Jesse Baird, 26, and partner Luke Davies, 29, claiming he acted in self-defence during separate struggles with the men.
Damon Wilson, who Mr Baird saw casually for a few months in 2023, testified about a long message he received from the accused after Lamarre-Condon spotted him and Mr Baird having breakfast.
"There are so many mind games being played," Lamarre-Condon allegedly told Mr Wilson in a message on Instagram.
"All I want to say is be very careful and trust your gut.
"It took me so long to recover from all the manipulation and he has now tried to make me look like the 'bad guy'."
Lamarre-Condon allegedly sent Mr Baird a text at roughly the same time saying: "I can see you and Damon having breakfast in Paddington".
Corey-Dean Thorpe meanwhile testified about his former long-term partner's state of mind in the months before he died.
Mr Thorpe told the NSW Supreme Court jury he remained close friends with Mr Baird after their separation.
In November 2023, three months before Mr Baird's death, Lamarre-Condon posted an Instagram story with an internet picture of a bunch of flowers and a message.
The Crown alleges the officer falsely implied Mr Baird, who could not see the post, had sent them.
After Mr Baird allegedly found out, he told Mr Thorpe he was fearful of Lamarre-Condon's escalating behaviour.
"I never heard him so scared," said Mr Thorpe, who was deeply emotional throughout his evidence.
"He just kept repeating: 'He's got a gun'."
Fears that the officer would make a false allegation to ruin Mr Baird's television career were also at the front of mind, Mr Thorpe said.
Three months after he raised his concerns with Mr Thorpe, the TV presenter and new partner Mr Davies were killed when Lamarre-Condon entered his house disguised with a motorcycle helmet and armed with his police pistol.
Another close friend of Mr Baird tearfully recounted how close his mate and Mr Davies became before the fatal incident in February 2024.
"There was something about Luke that just lit Jesse up - they were the real deal," friend Matthew Edwards said in court on Wednesday.
Members of Mr Baird's family became visibly emotional in the public gallery of the NSW Supreme Court during Wednesday's testimony.
Under cross-examination, Mr Edwards said posts the police officer made on Instagram lying about his relationship with Mr Baird did not rise to his friend being worried about his safety.
"Words 'unsafe' coming from Jesse, no," Mr Edwards said.
"Uncomfortable, yes."
Defence barrister John Stratton SC has told jurors Lamarre-Condon did some "stupid things" to Mr Baird but his behaviour was never threatening.
Lamarre-Condon has suggested his gun went off twice while struggling with Mr Baird, killing the 26-year-old, while Mr Davies shot himself while later wrestling the police officer.Â
Later in the trial, the jury of 15 men and women is expected to hear from the officer's close friend about a conversation the pair had straight after Lamarre-Condon left Mr Baird's house on February 19, 2024, prosecutor Brett Hatfield SC said.
After arriving in a car he hired in his mother's name the day before, Lamarre-Condon asked Ethan Lynch to not judge him for killing the two men.
Mr Lynch asked how he did it and his friend answered, "with a gun, pew pew," while making a hand gesture of firing a gun, Mr Hatfield said in his opening address.
Mr Lynch later gave statements to police about what Lamarre-Condon told him but continued to visit the officer in custody for months after the killings.
The trial continues.
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