An Auckland man accused of a double stabbing that killed a visitor next door initially told police he had nothing to do with the attack.
Dustin La Mont, 26, is accused of murdering 24-year Whangarei man Nathan Pukeroa outside a house in suburban Mount Albert in the early hours of December 3 and grievously wounding Devaray Junior Cole-Kuvarji in the same knife attack.
Prosecutors say La Mont became obsessed with getting his neighbours at 21 Renton Road evicted because of frustration with their mid-week parties and Mongrel Mob visitors and went so far to film and monitor them.
On the night of the killing, La Mont sent out a series of angry tweets about a loud party, grabbed a knife and went towards next door, prosecutors say.
The defence says La Mont was defending himself from the pair.
On Monday, the jury at the High Court at Auckland was played a video in which La Mont told a police officer interviewing him there had been a loud party next door but that he had gone outside to check on a fire alarm going off down the street.
He said an elderly woman had come out from the house where the siren was going, telling him she had left her cooking on, after which he returned home and had a shower.
During the interview - recorded the week after the attack - La Mont tells the officer he spent the night on his phone, saying he was "obsessed" with it, before describing how he had self-harmed after "thinking too much".
His girlfriend had later alerted him to something happening outside, he said.
"I was too deep in my own self-hatred to notice what s**t the neighbours were up to," he said.
Prosecutors say La Mont bleached his clothes and shaved off his beard after the attack.
Asked explicitly if he had gone to the front of No. 21 and "stabbed those two guys", La Mont replies "no", and then explains he shaved the beard because he didn't like his appearance.
He said when he later tweeted he was looking forward to "getting his statement out of the way" he meant he wanted to tell the police about his neighbour's gang activities.
Mr Cole-Kuvarji, 23, earlier told the court he and Mr Pukeroa both happened to be visiting Auckland and had agreed to meet at No. 21 earlier that day.
He said they saw a man staring down the driveway and followed him up to the street, where he stabbed each of them in the neck without warning.
The trial is set down for three weeks.