Leaving his workmate lying in a pool of blood inside an Otara garage, Teina Taunga sat in a car listening to music with a few more cans of bourbon and coke, prosecutors say.
Cleaner Gary Moore, 57, was found dead by his partner at his south Auckland home on the morning of July 31 last year.
His co-worker at Fisher & Paykel, 29-year-old Taunga, is standing trial accused of murder.
Prosecutor Yelana Yelavich on Monday told the High Court at Auckland that Taunga had beaten Mr Moore with a pool cue and then choked him after the pair started smoking meth and cannabis at about 4am.
The pair - who occasionally socialised outside of work - had been drinking and playing pool from about 10pm - Taunga bringing a box of Woodstock bourbon and cokes and a bottle vodka with him - before they began smoking P, she said.
While it was not clear exactly what occurred next, pathologists' evidence was consistent with Mr Moore being beaten with a pool cue along his head and body, she said.
As Mr Moore lay in his own blood, rather than calling an ambulance, Taunga went out to the driveway and sat in Mr Moore's car with a few cans of drink, listening to music until police arrived about four hours later, Ms Yelavich said.
Mr Moore's partner of 30 years, Aroha Stills, had been sleeping upstairs from before Taunga arrived and never heard the commotion.
On Monday she told the court she went into the garage after finding their security door open in the morning.
"I thought he was still warm. But obviously he was cold," she said holding back tears.
"He was face down. "
Ms Still said she ran upstairs and called emergency services
In interviews after his arrest soon after, Taunga would admit to choking Mr Moore, saying the pair had gotten into an argument and he had been trying to keep his workmate from attacking him, Ms Yelavich said.
Opening the defence, lawyer Philip Hamlin said while Taunga had always accepted he had killed Mr Moore, he had not intended to do so.
"Never did he think or realise that what he had done had caused his death," he said, adding Taunga had gone to check on Mr Moore later and thought he was fine.
"There's no motive."
A "toxic cocktail" of drugs had been involved, he said.
The trial is expected to last two weeks.
- NZ Newswire