Dustin La Mont had no reason to use lethal force when he fatally stabbed his neighbour in the street, the Crown says.
Mr La Mont, 26, is on trial in the High Court in Auckland, where he has denied murdering 24-year-old Nathan Pukeroa and critically injuring Devaray Cole-Kuvarji in December last year.
Mr La Mont's lawyers said their client was acting in self-defence when he was confronted by the two men who were aggressive, connected to gangs and who were protecting drugs and cash.
In his closing address to the jury today, Crown prosecutor Steve Haszard said Mr La Mont was obsessed with his neighbours and made complaints to police, noise control and animal control.
He would sometimes listen to the noisy parties for 20 minutes at a time, with his ear pressed up against the window of the room closest to his neighbour's house.
Mr Haszard said Mr La Mont also checked his neighbour's Facebook account 72 times and checked vehicles parked outside his neighbour's home 105 times in three months.
"He hated his neighbours at number 21 and said they were animals."
He said on one occasion Mr La Mont crept over to his neighbour's property and filmed them partying in their sleepout.
On the night of the killing another party was taking place and Mr Cole-Kuvarji was one of the party-goers. He was urinating in some bushes when he spotted Mr La Mont as he walked past and looked into the property before heading down the end of the street and into the shadows.
Mr Cole-Kuvarji described Mr La Mont as looking "suss" and Mr Haszard reminded the jurors that a vehicle connected to the party address had been broken into recently.
"In terms of why Mr Pukeroa went out, who knows? Very tragically, he's not here to tell us."
He said the two men confronted Mr La Mont, who acted with precision, and stabbed both men in the neck. He also said there was evidence to suggest Mr La Mont had the knife out of his pocket before the confrontation began.
"Only one party had a knife and only one walked away without a scratch."
Mr Haszard said Mr La Mont's argument of self-defence did not stand up to scrutiny.
"The Crown says there is absolutely no way - on any analysis - that the force he chose to use was reasonable or proportionate. It just wasn't."
Mr Haszard said Mr La Mont swung the knife in a roundhouse motion. He used so much force that the hilt left bruising on Mr Pukeroa's neck.
He also used excessive and lethal force instead of running down a driveway or scrambling over the wall at the end of the cul-de-sac.
Mr Haszard described Mr La Mont as a sophisticated liar who lied to his girlfriend and repeatedly lied to police, telling them he was in a garden shed self-harming at the time he was outside confronting his neighbour with a knife.
He said Mr La Mont showed no remorse or regret for what he did and sought to cover his tracks by dismantling the knife he used, bleaching his clothes and dumping the items on his way to work the next morning.
He also took to the social media website Twitter making disparaging comments about the man he had just killed.
"The use of lethal force must be reserved for the most extreme cases before it can be legally justified. That can't be the case here. It can't be. You can be sure of that," Mr Haszard said.
'There was an immediate danger' - La Mont's lawyer
However, Mr La Mont's lawyer, David Hoskin, said his client was approached by two men who had gang affiliations and were much larger than him.
Mr Hoskin said there was evidence that the two men were protecting a stash of drugs and cash in the house. Text messages shown to the jury revealed that other people at the address had paid $8000 for an ounce of methamphetamine on the day of the killing. They had also tried to buy $78,000 of the precursor drug, pseudoephedrine.
Mr Hoskin said the drugs and cash were in the house when the two men saw Mr La Mont and that was what drove them out onto the street. He said the men asked Mr La Mont if he worked for the police as they approached him.
There was shoving, Mr La Mont's shirt was grabbed and one of the men talked about smashing him.
"Two big men on one small man."
One of the men also threw a punch and there could not be any issue that Mr La Mont was protecting himself, he said.
"The attack couldn't be more imminent. I suggest without a defensive action, Dustin La Mont was only seconds away from being overwhelmed. There was an immediate danger that required immediate action."
He said his client was in a pure panic and had tried to walk around the two men but they blocked his exit.
Mr Hoskin said even if Mr La Mont had run, he would have been chased down.
He also addressed the evidence of Mr La Mont carrying a knife. He said there was evidence from Mr La Mont's cafe colleagues and his partner that showed Mr La Mont always carried a blade and often used it at work.
Tomorrow Justice Edwards will sum up the case before the jury retire to consider their verdicts.