A South Australian man felled a friend with one punch during an argument over who should buy the next round of drugs and then left his victim injured near a local hospital in a "dog act", a court has heard.
Glen Kerry Patterson has pleaded guilty to the manslaughter of Adrian Trett in 2018.
In the District Court on Tuesday, defence counsel Andy Ey said Patterson and Mr Trett had lived together for some time and had been drinking and taking drugs for more than 24 hours at the time of the incident.
An argument broke out between pair over whose turn it was to buy more drugs at which point Patterson punched his victim in the face.
Mr Trett had stumbled back and fallen down the stairs in their property at Mannum.
Patterson and another man then tried to take him to hospital using a mobility scooter but as they got near Patterson panicked, leaving the injured man on the side of the road.
Mr Trett had been found and admitted for treatment but died several days later.
The court was told Patterson has been affected by alcohol, drugs and a lack of sleep, but did not think his friend would die from his injuries.
"It was, in his words, a dog act," Mr Ey said.
He said Patterson was extremely remorseful over what he admitted was an unprovoked attack.
The 51-year-old was not charged until almost two years later but Mr Ey said his client was "in a strange way" somewhat relieved.
"It allowed him to fess up and accept that he was the cause of Mr Trett's death," he said.
The court was told that while the medical evidence was "neutral" on the question of whether Mr Trett had only suffered the one punch, both the prosecution and the defence asked Judge Ian Press to sentence on that basis.
However, Judge Press indicated he had some problems with that proposition and would consider his approach ahead of sentencing Patterson in November.
