In a landmark ruling, a man who beat his girlfriend to death in a fit of rage has been jailed for life, with a minimum non-parole period of 20 years.

Dylyn Davis, 26, beat his girlfriend Aroha Kerehoma to a bloody pulp in the Dominion Rd garage where they lived in Nawton, Hamilton, after becoming enraged that she had sent text messages to a former partner saying she felt unsafe.

Then he walked away, Kerehoma lying battered and motionless on the floor. She had initially survived the brutal assault that Davis subjected her to soon after midnight on Sunday, February 4, and may have lived had he called for an ambulance.

MARK TAYLOR/STUFF Dylyn Davis, 26, beat his girlfriend Aroha Kerehoma to a bloody pulp in the Dominion Rd garage where they lived in Nawton, Hamilton, after becoming enraged that she had sent text messages to a former partner saying she felt unsafe.

Later that night, as the Crown summary of facts reveals, he told an associate he had killed the 28-year-old Hamilton woman.

"I choked the bitch. She had it coming," he told him.

The associate asked him if he was sure she was dead.

MARK TAYLOR/STUFF Aroha Kerehoma's family had about 40 T-shirts printed bearing her face and the inscription "Justice for Aroha".

Davis replied: "I made sure I finished the job. I was choking her out while she was gargling on her blood."

Davis was sentenced on Tuesday before a packed public gallery at the High Court in Hamilton by Justice Paul Davison QC.

As the murderer departed someone in the public gallery called out to him: "You're out of here, bitch".

MARK TAYLOR Stuff NZ Aroha Kerehoma's family, led by her mother Luana Kerehoma, emerge from court following the sentencing.

It was his third strike under the "three strikes" regime and the first third strike murder sentencing to happen under that legislation, introduced in 2010.

That meant the prospect of a mandatory sentence of life imprisonment without the possibility of parole - unless it would be a manifestly unjust or grossly disproportionate penalty for the defendant.

The judge decided it was.

MARK TAYLOR Stuff NZ Aroha Kerehoma's aunt Judi Waugh and sister Horiana Kerehoma speak to media outside court.

This was partly because of Davis' relative youth, and also because the brutality and callousness of Davis' deeds were not as great as other, comparable cases.

But while he stepped back from applying the full impact of the available law, Justice Davison QC still imposed a hefty sentence on the "cowardly" Davis.

"You are someone who cannot be trusted in the community. You cannot be trusted to restrain yourself from your recourse to violence."

KELLY HODEL / STUFF The family of Aroha Kerehoma gathered outside the High Court in Hamilton following Dylyn Davis' sentencing.

Davis and Kerehoma, also known as Aroha Toka, had been in a relationship for about five months when he killed her.

Her last day alive had started without incident. About 2pm that Saturday Davis bought alcohol for a planned evening of drinking and playing music.

Between 7.30pm and midnight, Kerehoma engaged in a text message conversation with her former partner, in which she said she did not feel safe, and did not like staying home with Davis. She also said Davis had been hitting her.

FACEBOOK Aroha Kerehoma was killed by Dylyn Davis in a Nawton garage.

Her final message was sent at 11.58pm.

Not long afterward, Davis took the phone off Kerehoma and checked her messages. He became angry, and then violent, rendering her unconscious to the point where she died from her multiple blunt force head injuries.

A post-mortem examination laid out the damage in stark detail. Her nasal bones had been driven back into her skull cavity. There were fractures of both orbital wall structures around her eyes. There were numerous fractures to the base of her skull and right temporal bone. There were bruises on her brain matter on both sides. There was bruising, abrasions and lacerations to her entire face and scalp and haemorrhaging in both eyes.

There was also bruising to her chest, torso and left shoulder. A CT scan found air in her bowel, suggesting it had been perforated.

The examination report found there was no pattern to the injuries that suggested Davis had used a weapon. They were, however, consistent with the use of fists.

The examining pathologist could not rule out the possibility that the outcome for Kerehoma may have been different, had an ambulance been called immediately.

But Davis did not call an ambulance after beating her to a pulp. Instead, he changed his clothing and walked to an associate's house. Another associate picked him up, and it was to this man that he admitted he had killed Kerehoma.

He then visited another associate and spent the remainder of the night there. He did not return home until 1.30pm on Sunday.

Once there, he phoned an ambulance, telling the operator he had returned home to find his partner beaten.

When ambulance staff arrived, it was clear Kerehoma had been dead for hours.

An examination of Kerehoma's phone revealed that after her last message was sent just before midnight, her former partner had texted her at 12.08am, 12.15am and at 12.31am - all with no response.

A check of Davis' phone found he began a series of phonecalls to his associates at 12.33am.

He had been released from central North Island's Rangipo Prison on August 12, 2017 after serving a two years and four and a half month sentence for aggravated robbery.

He was subject to special conditions for six months following that date.

A parole board spokesperson confirmed Davis was released at his sentence end date and was not on parole at the time he killed Kerehoma.

After the sentencing, Kerehoma's aunt Judi Waugh said she was "extremely happy" with the minimum 20-year sentence.

"We wanted more. We were praying for more ... but he will stuff up in jail."

Dozens of Kerehoma's family were at court to hear the outcome, many adorned in specially-printed T-shirts bearing the inscription "Justice for Aroha".

Also there was Hayley Heke from the Sensible Sentencing Trust, who said Davis deserved to be "behind bars for life".

"You know that prick smiled at everyone when he walked out? You probably missed that," she said.

