New Zealand's first serial killer Hayden Poulter is to be released on parole, but where he will live remains unknown.

Poulter was sentenced to life imprisonment in 1997 for the rape and murder of sex worker Natacha Hogan in an Auckland park.

A nun walking her dog found Hogan's body, and the street was immediately on guard as police hunted for her killer.

SUPPLIED The scene where Natacha Hogan was murdered by Hayden Poulter.

The fear reached fever pitch when days later Poulter, a labourer living in Māngere, south Auckland, wrote to media promising he would kill again – and he did.

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A week after Hogan's death, Poulter walked into a Fort St massage parlour and stabbed the parlour's manager, Herbert Norris, and Thai worker Ladda Nimphet.

SUPPLIED Natacha Hogan, speaking about her friend Jane Furlong's disappearance to a documentary crew in 1993.

Another worker was also stabbed, but survived.

Later that day, Poulter turned himself into the Auckland central police station by leaving a bloodied knife on the front counter.

In interviews with assessors pre-sentencing, he said he'd never paid a prostitute but said the recent imprisonment of his girlfriend – a sex worker – had triggered something in him.

After his arrest, he told police that his second persona – "Hell" – had driven him to the murders.

Poulter became eligible for parole in 2011. Since then he has been inching his way towards freedom.

At a hearing last year, the Board hinted at the fact Poulter was getting close to being freed, and on Tuesday confirmed he would be released later this year.

Its decision detailed how for the past few years Poulter had been progressively given more responsibility.

That included 20 controlled releases from prison.

"Those releases have been to a range of venues and only positive reports have been returned," the report stated.

He would be released in June with a number of conditions which included not drinking alcohol for the rest of his life.

He would also be banned from contacting his victims, the media, or prostitutes, and subject to GPS monitoring, the Board said.

A psychologist's report from earlier this year concluded Poulter had "flexibility of thought". He was assessed then as having a moderate risk of general offending and moderate to low risk of sexual offending.

His proposal of release to a rural address with family members, where work would be provided, was considered appropriate after assessment by the psychologist.

"After consideration of all the material presented we are satisfied that Mr Poulter has sufficiently reduced his risk, that he can be released on parole subject to conditions which are extensive and will support his release into the community," the decision read.

Where Poulter will be released is unknown, but he has been banned from going to the Auckland region.

Hogan, his first victim, was a friend of Jane Furlong who famously vanished from Karangahape (K) Rd in the 1990s. Furlong's murder has never been solved.