The jury in a trial of a man accused of fatally stabbing a friend during an argument over a box of pre-mixed drinks has retired to consider its verdict.
Papakura man Ben Bosch Herkt, 39, is charged with murdering 32-year-old Matthew Greenslade who died after being dropped off at a south Auckland medical clinic with stab wounds on November last year.
The court has heard from the Crown how the two men got into a fight over a box of Cody's bourbon and cola while drinking at Mr Greenslade's house in Papakura.
Herkt ran to a neighbour's house and asked for a knife, before returning and stabbing Greenslade seven times in the head, neck and chest, prosecutors said.
The defence didn't dispute the attack but argued it was a case of manslaughter, not murder.
In summarising the evidence in the High Court at Auckland on Thursday, Justice Simon Moore told the jurors the key question was whether Herkt intended to kill at the time of the attack.
He said the defence had argued Herkt suffered from paranoid schizophrenia and the anti-psychotic drug he was taking was affected by the alcohol he was drinking.
"If you think it's a reasonable possibility that he didn't realise Matthew Greenslade may die because of either the alcohol or the effect the alcohol on his medication ... you must find him not guilty of murder," he said.
The defence argued the inexplicable escalation of a "silly fight" was evidence Herkt was confused.
"I didn't think, I didn't think. I was in angry mode ... I didn't think. I should have just shook his hand. He had won there," the judge quoted Herkt as telling police.
But the prosecution said Herkt had been given his medication and there was nothing to suggest he was suffering symptoms of his mental illness prior to the time of the attack.
Herkt drank frequently and that night was no different, prosecutor Gareth Kayes said.
A nurse told the court she was not concerned at all about Herkt's mental state prior to the attack but said alcohol affected his medication and condition, Justice Moore said.
During the trial, Greenslade's neighbour said Herkt came to his house bloody-faced, asking for a bat, but when he handed the accused a broken handle, Herkt asked for a knife instead.
The Crown argued that proved he thought the handle wasn't enough of a weapon for what he intended, Justice Moore said.