Justice Minister Amy Adams has appointed a retired Australian High Court judge to look again into David Bain's innocence as the one-time prisoner seeks compensation.
Ian Callinan starts on Monday and expects to report back in six months.
He will be the second international judge to assess Mr Bain's claim for compensation for wrongful conviction and imprisonment.
Mr Bain spent 13 years in prison after being found guilty of murdering his mother, father and three siblings in 1994 but was found not guilty at a retrial in 2009.
Last month, Ms Adams announced a fresh inquiry into his application for compensation because she said Cabinet did not have the information it needed to reasonably reach a decision.
In a report released in late 2012, former Canadian Supreme Court judge Ian Binnie concluded that Mr Bain was innocent and suggested he should receive compensation.
However, the then-Justice Minister Judith Collins then sought a peer review of that report, carried out by Robert Fisher QC, which criticised the findings as legally flawed.
Ms Adams selected Mr Callinan from a shortlist of retired judges with extensive criminal experience from both New Zealand and overseas jurisdictions.
"Mr Callinan is a distinguished and highly respected member of the Australian legal fraternity," she said.
"He brings a diverse mix of experience and expertise, following an exemplary career of nearly 40 years practice as a lawyer and nine years on the bench of the High Court of Australia."
She said he would bring a fresh perspective with the added advantage of being an inquirer from outside New Zealand, to remove any perception of influence of public opinion.
"I have every confidence that he will bring a dispassionate and fresh review to the case," she said.
"Mr Callinan's indicated that he has every expectation that he'll complete the review within six months."
She said he had been given similar instructions to those given to Justice Binnie but it had been made clear what was expected of him as a reviewer.
He will advise her on whether he is satisfied that Mr Bain has proven his innocence on the balance of probabilities. If that is that case, he has also been asked to say whether he believes Mr Bain's innocence has been proven beyond reasonable doubt.
Ms Adams said there should not be a repeat of Justice Binnie's report, which went outside its terms of reference in offering an opinion on whether Mr Bain should get compensation.
"The ministry has had good discussions with him and he's very clear as to exactly the scope of those instructions," she said.
"So I'm confident that we won't have a repeat of the misunderstandings we saw in the earlier report."
The new inquiry will cost about $400,000.
No expectation of 'no compensation' decision
Mr Bain's support team took legal action against Ms Collins, who they thought was biased against awarding compensation. They dropped that action last month.
Ms Adams said she was not going looking for a 'no compensation' decision from the new inquiry.
"No, all I'm searching for is to bring a robust and fair resolution to this matter. It's taken too long. I think everyone agrees that it's taken too long and needs to be resolved.
"That's why, as soon as the case was settled back in February, I've acted as quickly as possible to get a new direction from Cabinet and get a new reviewer appointed.
"All I want to see is a fair resolution based on reliable, dispassionate legal advice and I think Mr Callinan is in a good position to give us that."
She said her officials had spoken to Mr Bain's support team and they had raised no concerns about Mr Callinan's appointment.