A teenager used what amounts to a glass dagger when he stabbed another in the neck in a Grey Lynn street fight, the Crown says.
Vincent Angene Skeen admits he is responsible for the death of promising young rugby league player Luke Tipene, but denies a charge of murder.
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He is on trial at the High Court in Auckland, where Crown prosecutor Brian Dickey made his closing arguments today.
The court was told both Mr Skeen and Mr Tipene were outside a Halloween party last year when a street fight started.
Mr Dickey said Mr Skeen knew what he was doing when he used the beer bottle to lunge at Mr Tipene.
"That is an awful, awful lethal weapon - a smashed beer bottle - with a shard sufficient to cause the wounds, with a glass dagger to cause the wounds."
Mr Dickey said Mr Skeen acted in anger and showed off afterwards to his friends.
But Mr Skeen's lawyer, Lorraine Smith, said her client was just a teenager, had been drinking and was punched to the ground twice before he used the broken bottle.
"In October last year, Vincent Skeen was an adolescent who did something very silly and dangerous but there is no way that he did it with the sort of intent that elevates this to the murder."
She said her client would live with the consequences of his actions for the rest of his life.
Earlier, Mr Dickey went through Mr Tipene's injuries one-by-one and said when added up, they showed there had been at least eight lunges.
Mr Tipene had cuts to his arms, but the major wound was a 10 to 12cm deep wound to his neck which cut through the jugular vein.
Mr Dickey said everyone, no matter how young, knows that if you stab someone in the neck, you risk causing death.
He said Mr Skeen wanted to "get Mr Tipene, and get him good and that's exactly what he did".
Mr Skeen did not help Mr Tipene, Mr Dickey said but instead left the scene on Great North Road in Grey Lynn.
He said subsequent text messages between Mr Skeen and friends show the teenager hid from police and his only concern for Mr Tipene was when he got worried about the circumstances he found himself in.
He also went through the evidence of those that saw the fight and pointed to two independent witnesses in a nearby apartment building who saw Mr Tipene with his palms up and backing off.
But Ms Smith said Mr Skeen initially had no idea about how seriously he had hurt Mr Tipene.
She said her client yelled out he had just stabbed a guy straight after the incident and said no one who has committed murder broadcasts it.
Ms Smith said later in the night, when friends caught up with Mr Skeen, they said he appeared to have been crying and was in shock.
She said there was no evidence her client had murderous intent.
Ms Smith pointed to the evidence that Mr Skeen told friends shortly afterwards that he had "caked up" - slang for messing up.
She told the jurors that they had not heard from Mr Skeen because there was nothing he could say that would not be seen as self-serving.
Tomorrow Justice Woolford will sum up the case before the jurors retire to consider their verdict.