Jurors have begun deliberating in the manslaughter trial of an Auckland man accused of having intimidated a fellow Viaduct bar patron to the point the other man felt compelled to sprint away and jump into the nearby Waitematā Harbour, eventually drowning.

Prosecutors began their closing address today by quoting one of defendant Joniero Irving’s friends, a reluctant witness who described the circumstances of October 7, 2019, as “gangster shit seen only in mafia movies”.

The defendant texted a friend the next day, describing the chase as a “crack up” and stating “I wanted money, brother.”

“Such gangster behaviour has no place in a society such as New Zealand,” lawyer Mark Harborow said.

The body of James Harley David Jenkins, 24, was recovered from the harbour days after the chase.

During the trial, which began in the High Court at Auckland last week before Justice Timothy Brewer, jurors watch the confrontation between the two men unfold from multiple CCTV cameras. Irving and Jenkins first encountered each other that morning at waterfront bar Andrew Andrew, and while there was no audio the exchange seemed to have prompted Jenkins to hide a necklace he had been wearing in his partner’s bag.

Cameras outside the bar later showed Jenkins backing away with his hands up — then breaking into a sprint in the opposite direction — as Irving approached him in the car park. Moments later, at 4.12am, Jenkins jumped from the pier into the water and swam 80 to 100m to the nearby ferry terminal, footage and witnesses indicated.

“He was tracking Mr Jenkins. He was pursuing Mr Jenkins,” Harborow said of the minutes that followed the splash. “This was a determined pursuit.”

After about 10 minutes, Jenkins partially emerged from the water, “assessing the situation, going up and down on the ladder to see if it was safe”, the prosecutor said, explaining that the defendant was hiding behind objects on the pier in an effort to lure the other man out.

“Once he was out of the water, he could rob him or beat him up - whatever he wanted to do,” Harborow said, pointing to witnesses who said the defendant was yelling, “I will f*** you up. I am going to f***ing smash you.”

The defendant was also yelling aggressively about a $10,000 necklace that he said belonged to him, one witness recalled.

Eventually, Jenkins climbed onto the ferry while a ferry worker barred the defendant from getting on the boat. Jenkins then reached over the gap between the boat and the pier and handed the defendant the rings he was wearing, prosecutors said.

“He should have walked away at that point. He could have walked away at that point,” Harboro said of the defendant. “But he persisted.”

Joniero Irving appears in the High Court at Auckland charged with manslaughter. Photo / Jason Oxenham

At that point “truly cornered”, prosecutors said Jenkins jumped in the water for a second and final time at 4.32am.

Irving declined to testify or call witnesses during the trial. But defence lawyer Steven Lack pointed out during his closing address that his client left the scene about one minute after the second jump into the water. Jenkins wouldn’t disappear under the water until 13 minutes later, after refusing help from bystanders, Lack pointed out.

“I don’t condone Mr Irving’s behaviour that day as appropriate,” Lack said. “You might think ... that Mr Irving acted like a bully.”

Both men, Lack said, had been drinking and fell victim to “toxic bravado”. But the defendant had no way of knowing Jenkins had potentially lethal amounts of methamphetamine and cocaine in his system that morning, causing him to act abnormally, he argued.

He encouraged jurors to look beyond Jenkins’ “split-second decision” to jump back into the water, starting with testimony from one witness who described Jenkins hours before the incident as having been at a nine-out-of-10 level of intoxication.

“Mr Jenkins’ own conduct in remaining in the water ... after Mr Irving has left has broken the chain of causation,” he said. “He can’t be held legally responsible for the death.”

Witnesses said that Jenkins had been holding onto a pole for five minutes and had “ample opportunity to climb out” prior to sinking below the water, Lack noted. He theorised that Jenkins passed out as a result of a cardiac arrhythmia, which can be caused by excess methamphetamine and cocaine use, and drowned as a result.

“Regrettably, Mr Jenkins’ own conduct is what has caused his death,” Lack said, adding that he was not in the water long enough for hypothermia to have killed him. “It will be difficult for his family to contemplate, but that is what the independent evidence ... tells us.”

During the trial, pathologist Dr Paul Morrow said the primary cause of death had been drowning but that methamphetamine and cocaine usage might have played some contributory role.

It “simply doesn’t matter” if drugs played a part in the death because it was the defendant’s fault Jenkins was in a “lethal environment” in the first place, prosecutors argued. There can be multiple reasons why he died, but if the defendant’s actions played a not insignificant role in the death then he’s still guilty of manslaughter, Harboro said.

As for not getting out of the water sooner, it makes sense that Jenkins might still have been afraid given that the defendant had tried to lure him out by hiding earlier, Harboro added. And while he wasn’t in the water long enough for hypothermia to have caused death, he was in long enough that symptoms of hypothermia’s onset such as “clouded judgment” could have affected his actions, he said.

“Mr Jenkins died because of the defendant’s behaviour — it is that simple,” Harboro said. “The defendant chased, he hounded, he threatened and he stole. But he wanted more.”