Christchurch noisy neighbour murder: Tristan Locke loses ‘unorthodox’ appeal

Tristan Locke appearing at the High Court in Christchurch for the September 2020 murder of Mark Cowling in Edgeware. Photo / Kurt Bayer

A Christchurch man who stabbed his neighbour to death with a kitchen knife during a long-running dispute over loud music has lost what the Court of Appeal has described as an “unorthodox” attempt to throw out his conviction.

US-born Tristan Ross Locke, 33, who moved to New Zealand with his mother when he was 8, was sentenced last year to life in prison with a minimum period of imprisonment of 10 years after a jury found him guilty of murder.

Jurors in the High Court at Christchurch previously heard that Locke went to the home of Mark Graham Cowling, 44, on Father’s Day in September 2020. Locke had been playing music loud, but it was he who got enraged to the point of violence over Cowling’s calls to noise control and having cut power to his flat.

“This is a terribly tragic case,” Justice Murray Gilbert began in a 19-page judgment released this afternoon, noting that Cowling had been living with his partner and their baby and Locke was living alone with autism spectrum disorder and mental health issues.

The defendant had tested neighbours’ patience for months with his loud heavy metal music, causing one elderly neighbour to take out her hearing aids and stuff toilet paper in her ears, the court was told. They had contacted authorities and the landlord, but when that didn’t work, Cowling began repeatedly turning off his neighbour’s power.

Listening to very loud music had been one of Locke’s coping mechanisms for his mental health issues.

Locke didn’t deny having stabbed his neighbour, but his lawyer argued at trial that he didn’t have murderous intent. Representing himself on appeal, he repeated the argument.

Christchurch resident Mark Cowling, 44, was fatally stabbed by his neighbour Tristan Locke in September 2021.

“Mr Locke felt at risk because Mr Cowling had earlier threatened to drive a digger through his house,” the Court of Appeal said, summarising his defence. “Due to his mental conditions, he took this threat literally and genuinely feared for his personal safety.”

But the Crown pointed jurors to a letter that Locke wrote to his father six months after the stabbing that they described as showing he clearly did have intent.

“At least if I never get the chance I got one useless New Zealander and got to watch him die like a bitch,” the letter stated. “Classic New Zealand male bravado gone wrong. I hate them all, not enough of them can die. If they don’t want people to die they should probably educate them better, but they would never listen to little old me.”

Locke listed 20 grounds for his appeal, almost all of which were described by the court as “irrelevant in the context of an appeal against conviction ... namely whether the jury’s verdict was unreasonable, or a miscarriage of justice has occurred”.

“His grounds of appeal are unorthodox but in general terms he views himself as a victim who was harassed and provoked by Mr Cowling,” Justice Gilbert wrote. “He also claims to have been failed by various government institutions, including the police and mental health services. He contends he was ‘an unwilling participant in the whole event’ and Mr Cowling’s death was ‘purely accidental’. He maintains that he did not act with murderous intent.”

The grounds of appeal included an allegation that his neighbours had breached the Human Rights Act by discussing his mental condition, that police violated the Bill of Rights Act by failing to protect him from his neighbour and an allegation - described by the Court of Appeal as a “wholly unsubstantiated assertion” -that trial transcripts had been altered.

The appellate court found that it could evaluate Locke’s issues with the admissibility of the letter to his father, testimony from a detective and the reasonableness of the jury’s verdict.

“We are satisfied there was more than sufficient evidence to justify the jury’s verdict that Mr Locke acted with murderous intent when he stabbed Mr Cowling three times in the chest,” the justices decided. “Even if Mr Locke may not have intended to kill Mr Cowling when he stabbed him, there is ample evidence that this was a reckless killing.”

The justices did note, however, that their evaluation did not include an assessment of the sentence Locke received.

“...There may be other submissions that could be made in support of a sentence appeal, particularly focusing on Mr Locke’s mental health issues,” the justices said. “If Mr Locke wishes to pursue an appeal against sentence, we strongly encourage him to seek legal advice without delay.”