A woman accused of killing her mother's partner thought he was about to attack her with a meat cleaver, her lawyer has told a court.
Daryl Kirk, 20, has pleaded not guilty to murdering Adam Watkins. Her lawyer told the High Court in Wellington she fatally shot him in self-defence.
The court was told Ms Kirk and her boyfriend, her mother, Mr Watkins and a few friends were at the family home when an innocuous argument caused her mother's partner to lose his temper.
He grabbed a meat cleaver and told everyone to get out.
After things spilled out into the street, Ms Kirk ran upstairs, pulled her boyfriend's semi-automatic rifle from a drawer and fired six shots at Mr Watkins, who was hit three times in the neck, chest and back.
In his opening address to the jury, her lawyer, Mike Antunovic, said she was followed by Mr Watkins and was trapped in her bedroom.
"He was armed with a lethal weapon and coming at her. She thought he was intent on striking her," he said.
"He was not deterred by the gun when she presented it at him to warn him away. The then 19-year-old woman, who was the target of his rage, used the gun in self-defence."
Mr Watkins stumbled out of the house, collapsed on the driveway and died in the arms of Ms Kirk's mother, Kelly Kirk.
Kelly Kirk has since been sentenced to home detention for moving the meat cleaver under Mr Watkins' body, while Ms Kirk's boyfriend, Kyle Barnden, has been charged with illegally owning the gun.
In response, Crown lawyer Seamus Woods said Ms Kirk did not need to match violence with violence.
"No one was in immediate danger at the point Ms Kirk elected to go back inside the house and arm herself with the rifle," he said.
"In fact, at that critical time, each person was outside the house with an unobstructed exit onto the road and out of harm's way."
Ms Kirk did not need to shoot six times, and the fact Mr Watkins was shot in the back showed he was fleeing, he said.
Mr Watkins had a dysfunctional, stormy relationship with her mother, which sparked her reaction.
The trial is set down for two weeks.