Bio O'Brien sits in the dock at the Auckland High Court for sentencing for the manslaughter of Jasmatbhai Patel.

A Tuvalu national who attacked and killed an elderly man in a road rage incident has admitted another assault despite convincing authorities he shouldn't be deported because he was a low risk to the public.

Bio Talakatoa O'Brien pleaded guilty in the Pukekohe District Court this week to assaulting and threatening to kill a man who he cut in front of in a petrol station queue.

According to a summary of facts, O'Brien cut in front of the victim who was waiting in line at Pukekohe's Z Energy, on August 3.

SUPPLIED Jasmatbhai Pancha Patel, known to friends as Jasmat, died in Auckland Hospital's intensive care unit.

The victim told O'Brien, "There's a line mate," prompting O'Brien to begin swearing and yelling, the summary said.

READ MORE:

* Road rage killer faces deportation

* Road-rage killer jailed for 3 years

* Student jailed for killing pensioner in road rage attack

* Road rage victim's son says he can't forgive killer



NZPA Bio O'Brien appears in the Auckland District Court in 2009.

O'Brien then walked over to the victim and grabbed his neck with force.

As the man put petrol into his car outside, O'Brien continued to yell abuse including the words: "I will f***** shoot you in the head."

O'Brien, 35, was released from prison in 2012 after being jailed for three years for the manslaughter of 78-year-old Jasmathbai Patel.

Patel died in 2009 after becoming involved in a minor car accident with O'Brien, who was a Mount Albert Unitec student at the time.

This week the grandson of Jasmathbai Patel said the family had tried to move on from his death and said his father, Patel's son, found it too painful to talk about.

New Zealand First deputy leader Ron Mark called for O'Brien should be "booted out" of the country.

"He seems to think he's immune to being repatriated. Clearly the High Court has given him that impression," he said.

"The irony here is clearly the immigration office have deduced from an early stage that this man is not fit to be in the country.

"The courts overturned (the original decision) and members of the public have continued to pay the price."

According to media reports at the time, after O'Brien and Patel's vehicles crashed, the younger man pulled Patel from his van before hitting him around the face and body.

While Patel apologised and tried to defend himself O'Brien pushed him, causing Patel to fall backwards and hit his head on the kerb.

He fractured his skull and died the next day in hospital.

After serving his entire sentence O'Brien then became subject to a protracted legal battle to remain living in New Zealand.

The New Zealand Immigration and Protection Tribunal ordered his deportation back to the tiny Pacific Island nation of Tuvalu, which O'Brien left in 2000.

He had lived in New Zealand lawfully since then, aside from a three year period when he failed to renew his visa. He gained residency in 2008.

He appealed the decision, which was dismissed by tribunal.

O'Brien then sought a judicial review of the tribunal's appeal refusal and High Court judge Justice Simon France ordered the matter back to the tribunal for "reconsideration" in 2014.

At that hearing the tribunal was told by a psychologist that O'Brien was assessed as at a low risk of reoffending following "specific treatment and rehabilitation measures" including relationship counselling with his wife.

The tribunal described him as a having a "strong work ethic and a desire to improve himself" and a positive influence on his young daughter.

O'Brien argued that his deportation would adversely affect his family, who would remain in New Zealand, and he would be unable to find employment or familial support.

The tribunal ruled "it would not be contrary to the public interest for (O'Brien) to remain in New Zealand" after finding his deportation would be unjust or unduly harsh.

Immigration New Zealand said that O'Brien would only be eligible for deportation again if he was jailed for more than five years for the latest offences.

Residents can be deported depending on how long after they were granted residency that they offended, and the length of the sentence imposed.

O'Brien was eligible under the third tier- when a New Zealand resident commits an offence within 10 years of being granted residence- however the court must impose imprisonment of a term of at least five years for deportation to be considered, a spokesman said.

The maximum penalty for common assault is one year jail, and seven years for threatening to kill.

​O'Brien will be sentenced in November.