A man who fatally stabbed a sleeping squatter, in what WA's Chief Justice described as an "utterly senseless" murder, has been sentenced to life with an 18-year minimum.
David Morris Best, 59, used a large knife to inflict a single stab wound in the chest of 23-year-old Roy Erwin as he slept on a mattress in a shed at the rear of a vacant property in Mandurah in February 2019.
That property adjoined Best's home, and the Supreme Court was told he became angry after seeing Mr Erwin taking cigarette butts from his backyard.
He had confronted Mr Erwin and told him to leave, although only hours before the fatal stabbing he had showed him an act of kindness by giving him a can of stew, a bottle of water and cigarettes.
The court heard Best had been drinking for several hours before the stabbing.
He had also sent his son a text message before the murder, saying he would not be at work the next day because he had "carried out a bit of his own justice" and would have to go to the police station to tell his "side of the story".
Victim left unchecked after stabbing
The court heard immediately after plunging the knife into Mr Erwin's chest, Best left the shed and did not go back to check on him or call an ambulance.
Two days later, when he saw police at the property, he panicked and fled down south, where he disposed of the murder weapon before being arrested.
Best pleaded not guilty to the murder charge, arguing he had not intended to kill Mr Erwin.
He first stood trial in August last year, but it ended with a hung jury.
The retrial took place in January this year and he was found guilty.
'Baffling' and 'perplexing' murder: Chief Justice
Chief Justice Peter Quinlan described the case as "baffling" and "perplexing", saying there "was no reason" for it, and Mr Erwin's death was "utterly senseless".
"How you have gone from a simple act of kindness to an appalling act of violence is only something you can answer," he said.
The Chief Justice said he did not accept Best's claim that he did not intend to kill Mr Erwin, finding instead that he knew exactly what he was doing.
"You knew the effect the wound would have on him.
"There was utterly no reason for you to attack Mr Erwin … it was completely unprovoked and he was completely defenceless and vulnerable."
The Chief Justice also highlighted that the next day, when Best was sober, he had not checked on his victim and instead had taken steps to try to cover up the crime, including throwing away the gloves he was wearing.
Mother's life 'changed forever'
His mother Jeanne Bellgaart sat through both trials, and at Best's sentencing hearing on Friday she read her victim impact statement to the court, and addressed Best directly
Through tears, she said the moment she was told that her son had been stabbed her life "changed forever" and she "lost a part" of herself.
She said she still had nightmares in which she sees the vision of her son lying on the mattress and being left there, "like he didn't matter".
"How can such a horrific and gruesome attack happen?" she asked.
She told the court she now suffers from depression and anxiety and undergoes counselling.
Ms Bellgaart also said having to go through two trials had been emotionally and physically exhausting, but she was thankful for the support of her devastated family and Roy's friends.
Outside the court, Ms Bellgaart said "justice had been served for our Roy-boy".
"It's a good sentence, we're happy," she said.
