Peter Richard Holmes (26) was yesterday sentenced in the High Court at Dunedin to life imprisonment, with a minimum non-parole term of 12 years.
Holmes beat 23-year-old Jamie Ellis to death, partly because of an alleged sexual offence against a young woman Holmes fancied.
There was no evidence Mr Ellis had done anything, Justice Ronald Young said. Holmes "took the law into his own hands", launching a sudden and brutal attack on the unsuspecting man when any inquiry into the allegation should have been police business.
Holmes pleaded guilty in May to the April 15, 2011, murder of Mr Ellis.
Two other people, initially also jointly charged with the murder, recently admitted lesser charges.
Mark Carruthers (18), who was involved in the initial part of the attack, admitted a charge of manslaughter and is now on a lengthy supervision programme after his release from a two-year prison sentence.
His father, Dean Carruthers (48), admitted being an accessory after the fact of assault and wounding with intent to cause grievous bodily harm, and was sentenced this week to seven months' home detention and ongoing psychiatric counselling.
At sentencing yesterday, counsel John Westgate said Holmes had apparently been suffering from undiagnosed post-traumatic stress disorder at the time of the killing.
That condition, combined with excessive use of alcohol and an unfortunate set of circumstances on the day, resulted in events which were a tragedy for the deceased's family and for Holmes. He and the victim had been getting on well at a party in Oamaru.
Then there was a suggestion Mr Ellis had done something to the woman whose party it was and Holmes - "to his eternal regret"- decided to confront Mr Ellis in circumstances where it would undoubtedly have been clear there was going to be a physical confrontation.
It was a stupid and ultimately, fatally flawed plan, but Holmes never pre-determined it would go as far as it did, Mr Westgate said. In the months after his arrest, he could not explain why "it happened", although it became clearer after he began seeing a psychiatrist.
Holmes was not trying to justify what happened, but he was remorseful and had tried to write a letter of apology to the family -"for what that's worth", Mr Westgate told the court.
Justice Young said Holmes, the two Carruthers and Mr Ellis were all at a birthday party in Oamaru on the night of April 14. The Carruthers father and son left and went home to Dunedin but returned to Oamaru in response to a text from Holmes who enticed Mr Ellis into the car for a drinking session. They drove back to Dunedin.
Holmes stole another car and he and Mr Ellis travelled in that to Warrington where they met Dean and Mark Carruthers.
Mr Ellis, Holmes and Mark Carruthers all got out of the cars and then, "without any warning or provocation", Holmes attacked Mr Ellis. He and Mark Carruthers punched and kicked him and smashed beer bottles over his head, knocking him to the ground.
Mark Carruthers withdrew with a cut to his hand, but Holmes continued the "brutal" and "murderous" attack and eventually used a wheel brace to inflict a fatal head injury.
The body of Mr Ellis was dragged about 20m out into Blueskin Bay where it was found later the same morning.
His wallet was taken from his trousers and cash removed from it, two blood-spattered $20 notes later being used to buy food at an Oamaru service station.
The wheel brace used in the attack was later found in the sand about 20m to 30m from the body.
The car stolen by Holmes was abandoned at Shag Point before he went home, burned his bloodied clothing in the log burner then told his flatmates in graphic detail how he had killed Mr Ellis.
Early the next day, he drove Dean Carruthers' car to an area off Kaikorai Valley Rd and set it on fire.
Once police spoke to him, Holmes accepted responsibility for killing Mr Ellis, for attacking him without warning or provocation, and for inflicting the majority of the injuries, using bottles and a wheel brace, the summary of facts from Crown counsel Robin Bates said.
In total, Mr Ellis had 62 external wounds, 33 of them clustered about the head, face and neck, and 23 to the forearms and hands, the latter being consistent with defence injuries and indicating the use of blunt force weapons.
Two particularly forceful blows virtually amputated one of his left fingers and caused a deep wound to his outer right forearm. A deep laceration to the head corresponded to a penetrating skull fracture and was consistent with the use of a wheel brace.
After the first few blows, Mr Ellis would have been incapable of fighting back, but Holmes had persisted in the violent attack, Justice Young said.
Victim impact statements from the family showed the deep pain they suffered from the young man's death. Their lives had changed forever and they felt an emptiness from the loss which could never be filled.
The judge took into account Holmes' previous convictions for violent offending, the level of brutality involved in the unprovoked attack on an unsuspecting young man, initially by two attackers, the use of weapons, including a wheel brace and severe wounds inflicted.
The only mitigating feature was the guilty plea, Justice Young told Holmes, sentencing him to life imprisonment. He ordered him to serve a minimum of 12 years without parole. On an unrelated assault and dishonesty charges from two weeks before the murder, Holmes was sentenced to concurrent two-month jail terms.
