On day three of the trial, the jury heard from a detective who took notes of Locke's comments while he was in custody hours after the incident.
Detective Michael Henderson-Rauter handled Locke while he was in custody, and informed him at 4.27am - less than two hours after the altercation – that Cowling had died from his injuries.
The police officer told the court that Locke responded by saying, "Oh wow, savage. F***".
Henderson-Rauter then arrested him for murder and read him his rights.
Asked if he understood that he was under arrest, Locke allegedly replied: "I'm going to be a New Zealand resident" and "I'm going to be here for a very long time."
Locke told the police officer that he was intoxicated and had been for the last week. But Henderson-Rauter observed that Locke walked without issues, did not appear intoxicated, and was not slurring his words.
Locke allegedly said his neighbour kept turning off his power and that he wanted a lawyer.
Accompanying him on a toilet break, the detective noted Locke saying, "That guy didn't deserve it."
Locke later allegedly said he was "pretty screwed" and that he couldn't be "put to death in this country" which was "probably a good thing".
While his fingernail clippings were being taken for DNA samples, Locke allegedly said: "Well, I'm f***** aren't I. But so is the guy who is dead now. We all make sick jokes."
He later allegedly added: "How did I even do that? F****** stupid" and "Death row, do me a favour."
The Crown earlier said that Cowling, his partner Rebecca McMaster, and their young child had been living in a block of five flats in Edgeware, when Locke moved in last June.
Cowling's household, and other residents in the block, complained that Locke listened to music at high volumes, with the first noise complaint coming on July 9.
Up to the day Cowling died, there had been a total of 21 noise complaints.
One neighbour, Enda Lynam, gave evidence yesterday to say the music coming from Locke's flat after he moved in was "horrific... to the point you could feel it".
"Tensions had been high for a while," Crown prosecutor William Taffs said.
A few weeks before the fatal incident, Cowling had gone to Locke's house and they had argued over "loud music", the court heard.
On September 5 last year, Cowling and his family got home about 4pm-5pm and allegedly heard Locke already playing loud music.
Noise control would be called four times that evening. It's alleged that Locke would turn the music down when noise control showed up – but resume once they'd left.
Security officer George Dimitru was called out that night. From outside the flats, he encountered "heavy rock, metal... very powerful".
He served a notice on Locke before moving on to the next job.
But the noise allegedly continued and a fed-up Cowling accessed the fuse box which serviced the whole block of flats and cut the power to Locke's house three times.
On the third occasion, at 2.25am, the Crown alleges that Locke took a knife and stabbed Cowling in the chest, causing a 10-12cm fatal wound that injured his heart and lung.
Locke phoned 111 and he was arrested at the scene, with a knife found on the path outside.
The emergency calls were played to the jury yesterday, where Locke is heard asking emergency service to come to the address "right now... stabbing".
When the call taker asked where the address was, he became frustrated, saying, "Please stop kidding, it's serious... He's f****** bleeding a lot... I'm shouting because this is so serious".
"It's not quite my fault... I'm a reasonable person," he's heard saying.
When the call taker asked Locke for his name, he replied: "We'll wait for that. Get here. This is very serious, get here. I'm not answering anything else right now without a lawyer."
The trial, before Justice Cameron Mander, continues.
