The former senior constable has pleaded not guilty to the murders of his ex Jesse Baird, 26, and Luke Davies, 29, saying he acted in self-defence.
One of the officer's friends told the NSW Supreme Court on Thursday she received a call from Lamarre-Condon on February 20, 2024 - the day after Mr Baird and Mr Davies were allegedly murdered.
"He told me he'd stolen some police files from the commissioner to do with COVID and wanted me to get rid of a phone," WA resident Stacey Parker told the 15-member jury.
"I had to be 30 or 40 kilometres from my house, turn the phone on then turn it off and then throw it into a body of water."
Ms Parker never received the phone despite Lamarre-Condon telling her he would send it by express post.
The jury has previously heard Lamarre-Condon took Mr Baird's phone and used it to message the 26-year-old's housemates, implying Mr Baird was taking a road trip to Perth.
Ms Parker first met a teenage Lamarre-Condon in Sydney in 2010 while they were waiting outside the Sunrise studio to try and get a photo with famous singer Pitbull.
They kept in touch and regularly met when Ms Parker came to Sydney once or twice a year, she told the court.
During the COVID-19 pandemic, Ms Parker - who attended many anti-vaccination protests - asked the senior constable how he could "push back against people fighting for their freedoms".
"He said it was the Devil's work," Ms Parker said.
After years of communicating on Facebook and Instagram, Lamarre-Condon suddenly asked on February 13 to move their chats to the encrypted app Signal.
Two days after asking her to dispose of the phone, Lamarre-Condon called Ms Parker again in a different mood, she told the court.
"There's two guys missing in Sydney, he used to know one of them and he was being set up," Ms Parker recalled the accused saying to her.
The following day, Ms Parker saw a news story mentioning Lamarre-Condon as a person of interest in the two men's deaths and a detail saying Mr Baird's phone had sent a message saying he was going to Perth.
"I became concerned," Ms Parker said.
The trial continues.
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