The man accused of killing Austin Hemmings has pleaded guilty on the morning of his High Court trial.

Mr Hemmings, 44, stepped between a man and a woman arguing in Auckland's Mills Lane in September, 2008, and was dubbed the "good samaritan".

The 44-year-old father of three was stabbed and staggered a short distance.

Police began a manhunt, ending in the arrest of Pauesi Leofa Brown.

Brown was to stand trial at the High Court at Auckland today but pleaded guilty before a jury was sworn in.

The plea means the trial will now not go ahead.

Outside the Auckland High Court today, Mr Hemmings' widow Jenny described the guilty plea as a "huge relief".

"The first of November has been a very important day for the Hemmings," she said.

"I'm just thankful that New Zealand is a safer place. Mr Brown will go to jail and serve a sentence."

Mrs Hemmings called on law-makers to make the carrying of knives in public illegal and a serious offence.

"There are many people being killed by the use of knives," she said.

"If you go and research the statistics on the internet you will be shocked."

"One week after Austin was killed, another man in the Napier-Hastings area was also murdered.

"We need to address this issue."

Mrs Hemmings thanked the police and the prosecution lawyers for their work on the case.

"They did a tremendous amount of work and informed us on everything at every step."

Mrs Hemming said the two years it took for Brown to finally plead guilty was a long time, but allowed the family to "gather their strengths".

"Initially it was frustrating, but it does give you time to think."

She said the plea gave the family a sense of closure.

The family plan to attend Brown's sentencing, which will be on December 10, with Mrs Hemmings hoping he would go away for "a long time".

"New Zealand doesn't need this man on the streets," Mrs Hemmings said.

Mr Hemmings' oldest daughter Meghann also spoke outside the court following Brown's change of plea and was pleased a jury trial would not be needed.

"It was really hard but at the same time to not have to go through two weeks of that is fantastic news," she said.

Craig Hemmings, Austin's brother, told Radio New Zealand he was hoping the maximum penalty possible would be imposed at Brown's sentencing next week.

He said this would send a strong message to New Zealand about knife crime.

At a depositions hearing last October, Crown prosecutor Kevin Glubb said Brown's cousin Diane Nonu, for whom name suppression has now been lifted, was working at an inner-city call centre and was on a cigarette break when she was confronted by the former partner of her friend.

"The defendant believed Ms Nonu had been talking about him behind his back and took exception and intended to have it out with her," Mr Glubb said.

As Ms Nonu backed away from Brown, Mr Hemmings approached the pair and asked what was happening.

"The defendant said: none of your business. Clearly Mr Hemmings sensed there was danger and stepped between the defendant and Ms Nonu," Mr Glubb said.

He said Mr Hemmings told Ms Nonu to run. Ms Nonu then told the person she was talking to on her cell phone to call the police.

Mr Glubb then said Ms Nonu got to the elevator and looked back to see Brown pull up his jersey with his left hand and saw a knife tucked into his jeans before he made a "fast thrusting forward motion towards Mr Hemmings" with his right hand.

He said Brown then approached Ms Nonu and punched her in the face twice before swinging at her stomach with his knife but missed.

Mr Hemmings stumbled out of the building along Mills Lane towards the intersection with Swanson St. He collapsed outside a medical centre where he got immediate help but could not be saved.

Mr Glubb said when police arrived at Brown's house to arrest him, Brown said: "How did you find me so fast?"

Ms Nonu told the court last October that she was related to Brown but only met him when her friend began seeing Brown.

She said she saw Brown on the footpath at the back of her building when she was on a break and waved to him while talking on her cell phone.

"He walked up to the kerbing and he was kicking at a stone, going around in a circle."

Ms Nonu continued on her phone until Brown approached her again.

"He started saying: What have you been saying about my family?"

She said he was angry, demanding and assertive.

Ms Nonu said Brown was "right up in my face" and she was "scared" as she backed away, Brown kept coming at her.

"There was a blue wall behind me and I didn't want to get trapped between him and the wall."

Ms Nonu said she was trying to sidestep Brown but he kept coming at her and looked aggressive.

She saw a figure out of the corner of her eye and called out.

"Sir, can you please help me, can you call the police?," Ms Nonu said.

She said the man, who later turned out to be Mr Hemmings, intervened and asked what was happening.

"[Brown] said none of your business, it's got nothing to do with you," Ms Nonu said.

She said Mr Hemmings put himself between her and Brown.

"Austin's back was a centimetre or two away from me and the same for [Brown]"

She said she then began "tugging" Mr Hemmings by the shirt "because I thought it might get violent and I didn't want him to get hurt,"

"He then turned to me and said to run, so I ran," Ms Nonu said.

Ms Nonu said she was still on her cell phone to a friend and told him to "call the cops."

"He was saying to me, what's wrong, I just kept telling him to call the cops."

Ms Nonu said she headed for the elevators of her building and turned to see Brown coming at her "walking very quickly towards me".

Ms Nonu said Brown lifted his jumper and she saw the handle of a knife sticking out of his jeans.

"He turned and then went towards Austin," she said.

Ms Nonu said Mr Hemmings had entered the building and was about 10 metres away before Brown approached him.

"I saw his left hand pull up his left side of his jumper as he did when facing me. I saw his right hand reach in and a movement of his right hand come down towards his waist and a really quick microsecond he thrusted really quickly and because I had seen the handle of the knife I realised he had stabbed Austin," Ms Nonu said.

She said she screamed and heard the noise of the elevator. She got in and pressed a button but just as the doors were closing, Brown got into the elevator.

"He put his right arm against my throat."

She said he put her right leg through the door-way so the elevator doors would not close.

"I was scared about what he was doing."

She said Brown had his forearm against her throat and was pressing with all his body weight.

Ms Nonu said Brown had the knife in his left hand and punched her in the face twice.

She said Brown then swung with his knife at her stomach, missing her by "a few centimetres".

Asked about the "swing", Ms Nonu said it was "similar to the way he stabbed Austin, very quick, with full force".

She said she pushed him away but Brown grabbed her work swipe card and her house keys that were on a cord around her neck which left a "deep red mark".

Ms Nonu said Brown ran towards the carpark and she went up to level two.