The partner of a man shot dead while she hid from him in a bathroom broke down in an Auckland court today as she recalled hearing the fatal shot.

Alan Gundry, 30, is accused of murdering Orewa man Gene Atkins on January 12 at Gundry's Rodney home, and unlawful possession of a firearm.

Mr Atkins' partner, Sarah Jane Dean, told a depositions hearing in North Shore District Court how she and Mr Atkins had had an argument that day over dinner arrangements.

The argument continued between their home and the house that Gundry shared with his partner, Nicole McDonald, and their two young children.

At one point, Mr Atkins kicked the headlights of her car, swung the door into her as she tried to get into the vehicle and threw two punches, hitting her with one of them.

Later at Gundry's house, Mr Atkins, who had been drinking, attacked another man who was trying to protect Ms Dean.

Ms Dean said she then went inside and hid in a bathroom, from where she could hear Mr Atkins asking for her whereabouts.

Gundry knocked on the door, told her that Mr Atkins had hurt Ms McDonald and that he had had enough, and went to get a gun.

Asked by prosecutor Ross Burns what she said to Gundry, Ms Dean began to weep, taking some moments to compose herself.

She said Gundry put ammunition in the gun and she told him: "You're not going to shoot him, are you? You're going to scare him."

She then heard two gunshots, before Gundry came back and told her: "I'm sorry, I'm sorry."

Under cross-examination by defence lawyer Graeme Newell, Ms Dean said Mr Atkins, who was on bail at the time of his death for allegedly causing grievous bodily harm, had shown similar anger towards her previously.

On two other occasions, he had taken it out on her car and on a third he had severely bruised her arm.

In his opening address, Mr Burns said at issue in relation to the murder charge was whether Gundry was acting in self-defence and, if so, whether the force he used was reasonable.

Mr Burns said that, during the confrontation, Atkins advanced on Gundry, who fired one shot which had no effect.

Gundry fired a second shot, which killed Atkins.

Gundry was on bail ahead of the depositions hearing, which began this morning and has been set down for two days.

- NZPA