A NSW Supreme Court jury delivered the verdict on Friday afternoon, apparently believing Nicholas Luke Martin's argument that he was in fear and defending himself when he killed Shahn Baker on February 3, 2022.
The jury additionally found Martin not guilty of a back-up manslaughter charge, securing the 30-year-old's freedom.
Martin admitted he stabbed the 42-year-old outside a social housing estate in Erina, on the NSW Central Coast, but his barrister argued it was due to Mr Baker's history of violence towards Maxie Wilson.
Shortly before the killing Martin had started dating Ms Wilson, who the jury was told endured an abusive, six-year relationship with the deceased.
Mr Baker was said to have arrived at Martin's house heavily drunk about 8.30pm, demanding to know why his ex-partner was staying at another man's house.
Martin's barrister, Antony Evers, said he acted out of self-defence because he heard stories of Mr Baker's history of violence from his girlfriend.
The barrister said Mr Baker had assaulted Ms Wilson multiple times, choked her, forced her to drink bleach, punched her in the stomach while she was pregnant and made multiple death threats.
Mr Evers said he became increasingly hostile towards his ex-partner in the month before the stabbing when he realised she was not coming back to him,
"You guys are going to f***ing learn a lesson, I f***ing swear to god," Mr Baker said in a voicemail message left on Ms Wilson's phone.
Mr Baker also text messaged one of Ms Wilson's friends: "I'll break you and your f***ing family like you're doing to me."
Mr Evers told the jury the threatening messages and the alleged history of violence made Martin feel he needed to defend himself in the way he did.
"Neither law nor logic requires you, if you're defending someone else, to wait until they've been turned into a bloody mess to intervene," he told the jury.
Crown prosecutor Liam Shaw had asked the jury to dismiss the self-defence argument and find Martin guilty.
"He was the aggressor. He was a willing fighter," he said.
"He took the double-edged knife with him to confront Shahn Baker out of bravado."
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