The man lawyers say framed accused killer Thomas Bednar for the murder of his mother staked out the suspect's home for hours on the night the crime was discovered.
Bednar's barrister John Desmond claims 54-year-old Bednar is being framed, and that family friend Danny Cohen is the one who killed 78-year-old Judy Bednar in her Chelsea home in May 2021.
Bednar is standing trial for murder in Victoria's Supreme Court and has pleaded not guilty.
Mr Cohen, a family friend, gave evidence on Wednesday that he parked his car outside Bednar's home and watched it for more than an hour the night Mrs Bednar's body was found.
But he admitted despite making multiple statements about that day, he never mentioned it to police.
He also left it out of a timeline of his movements that day when questioned by Mr Desmond.
"My family was fearing for safety. I watched where Tommy was going because they hadn't arrested Tommy yet," he said.
He claimed he left it out of the narrative because nothing happened and it was irrelevant.
"Do you seriously think it would be irrelevant that you had been sitting outside a house away from Bednar's house for about an hour or so on the evening you have been nominating him as the murderer?" Mr Desmond asked.
Mr Cohen replied: "Why would I be staking his house out if I was part of the murder?"
Mr Cohen, who sometimes described himself as Bednar's step-brother or half-brother, also told the jury he had access to Mrs Bednar's doorbell camera and spoke through it to officers who discovered her body during a welfare check.
"I'm looking after Judy. I'm looking after her welfare. Ask her, she'll tell you," Mr Cohen told an officer at the door through the camera.
"Did something happen again today? Is Judy OK?"
When police questioned Bednar he told them he thought he was being framed.
Mr Desmond said Mr Cohen was a viable alternative suspect and it was a plausible possibility that someone determined to frame Bednar was the real killer.
"The defence says that it would be someone ... aware that Thomas Bednar had a negative attitude toward his mother," he said.
The jury also heard Mr Cohen raised Mrs Bednar's will in a conversation with her three days before she was killed.
He said it followed a conversation he had about her fears for her safety.
Prosecutor Mark Rochford KC told jurors Bednar sent abusive text messages to his mother in the year before her death, including one saying "it won't be long until the sharks eat your flesh".
The relationship between the mother and son broke down when Bednar was young. He went to live with a foster family at 15.
It's alleged Bednar killed her because he blamed his mother for a series of involuntary mental health admissions.
The trial is continuing.
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