A teenager high on a cocktail of drink and drugs has been jailed for nearly two years after killing an innocent bystander with a single punch.

Tyrone John Hugh Palmer was just 16 years old when he drank alcohol and took LSD and some cannabis and went out for a night out in Invercargill on April 9 this year.

In the early hours of the morning, he got into a confrontation with 40-year-old Matthew Coley outside the Night 'n Day store on Esk St.

At the High Court in Invercargill, Justice Nicholas Davidson noted that although Coley was intoxicated, "at all times was neither aggressive nor threatening".


"You punched him once to the head and he fell back on to the Night 'n Day store window, and then went straight to ground," the judge said.

"He had his hands by his sides when you hit him. To repeat, he was not confrontational in any way."

The punch was described and accepted as being delivered with considerable force. Coley had his hands by his side at the time.

It "clearly blindsided" Coley, the court heard.

"You ran from the scene and you told someone you know you had just 'king -hit' someone," Justice Davidson said.

Coley was rushed to hospital but passed away from his "unsurvivable" injuries. His cause of death was blunt force head injury resulting in acute subdural haemorrhage complicated by brain swelling.

Palmer, who is now 17, was caught by police and security staff in Don St soon after.

He admitted hitting Coley when first spoken with but initially said he acted in self-defence.

"You later changed the story and said the victim, Mr Coley, did not come at you, but you thought he was going to punch you, so you punched him in the head first. That is not an explanation which washes," Justice Davidson said.

Palmer's lawyer called for a sentence of home detention.

But Justice Davidson said he did not consider the purposes and principles of sentencing would have been sufficiently met by home detention.

The judge said he was "intensely troubled" by Palmer's use of drink and drugs at such a young age.

He said that combination must add to the risk of young people harming others, and themselves.

Justice Davidson sentenced Palmer to 22 months' imprisonment.