Supreme Court rejects appeal bid from Christchurch murderer who stabbed his neighbour

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

The Supreme Court has turned down an appeal bid from a Christchurch man who stabbed his neighbour to death during a dispute about loud music.

Tristan Ross Locke, 33, is serving life imprisonment with a minimum non-parole period of 10 years for the 2020 murder of Mark Graham Cowling, 44.

A High Court trial was told that Locke stabbed his victim with a kitchen knife after Cowling complained to noise control officers about Locke’s persistently loud heavy metal music, and turned off the power to his flat.

Locke didn’t deny stabbing his neighbour, but his lawyer argued at trial that he didn’t have murderous intent.

Locke later repeated that argument when representing himself in the Court of Appeal, but failed to have his conviction overturned.

He then tried to take his case to the Supreme Court, the country’s highest, but it has now turned down his application for leave to appeal.

In his Supreme Court application, made without a lawyer’s representation, Locke said that a miscarriage of justice would occur if leave was not granted and that the Court of Appeal was biased against him.

Mark Cowling was stabbed to death by Tristan Locke after he turned off the power to Locke's flat because of loud music. Photo / Supplied

However, the Supreme Court said in its judgment this week that Locke was seeking to reargue the facts of the case, on which a jury had delivered a verdict.

“Mr Locke had the assistance of very capable counsel at trial. There is no substantial allegation as to jury misdirection by the trial judge,” the Supreme Court justices said.

“Nothing put before us presents any likelihood that a substantial miscarriage of justice may have occurred.”

The judgment also said there was no foundation to suggest the Court of Appeal did not bring an impartial mind to its decision, “given the evident care and compassion with which it considered Mr Locke’s arguable grounds of appeal”.

Locke was born in the United States but moved to New Zealand with his mother when he was 8.

On Father’s Day, September 6, 2020, Locke’s long-running dispute with his neighbours about his loud music came to a head.

The courts have been told that Locke, who lived alone, used loud music as a coping mechanism for his autism spectrum disorder.

Neighbours complained to noise control 21 times over the course of two months.

Cowling, who lived with his partner and their baby, began turning off the power to Locke’s flat in the block of five in Edgeware where they both lived.

After one such incident, Locke went to Cowling’s flat and stabbed him with a knife.

High Court Judge Cameron Mander called the killing an “entirely senseless act”.

Judge Mander said Locke had a propensity to arm himself when facing conflict.

In 2012 he stabbed an associate in a fight and Locke had also approached a noise control officer outside his flat with a knife before the 2020 murder.