A man jailed for the high-profile kidnapping of his ex-partner on Great Barrier Island - during which he subjected her to a horrendous 38-hour ordeal - has been refused parole and will keep serving time for stalking and threatening another woman.

Nathan Boulter appeared before the Parole Board last month and it was revealed he had not undertaken any rehabilitation programmes for his most recent offending.

As a result, the board ruled he posed an undue risk to the community and refused to grant him an early release from prison.

Boulter became a well-known offender in January 2011 when he kidnapped his ex-girlfriend Nortessa Montgomerie on Great Barrier Island, sending the whole population effectively into lockdown as armed police launched a manhunt.

Nathan Boulter was jailed for eight and a half years in 2012. Photo / File

Boulter was on bail and facing a charge of assaulting Montgomerie, 21, when they lived together in Southland.

After the attack, Montgomerie left Boulter and moved back to her family on the remote island in Auckland’s Hauraki Gulf.

But Boulter could not accept the end of the relationship and went to great lengths to get to Montgomerie, travelling to Auckland and booking a ferry to Great Barrier under a false name.

He crept into Montgomerie’s family home and hid under the bed to wait until she and her new partner went to sleep.

He attacked the new partner, rendering him unconscious and as Montgomerie ran screaming, Boulter grabbed her by the hair and dangled her over a balcony.

He grabbed a weed grubber and threatened her with it before kidnapping her and dragging her across farmland.

Boulter hid Montgomerie in isolated bush and dragged her around the island to avoid the heavy police presence.

During the 38-hour kidnapping, Boulter told Montgomerie he had killed her younger brother and later took her behind a barn and strangled her until she blacked out.

He told her: “You scream for help and you are dead’'.

Nortessa Montgomerie is helped onto a Westpac Rescue Helicopter after her kidnap ordeal. Photo / Supplied

Boulter repeatedly punched the terrified woman in the face and head, causing a chip to her skull.

Eventually police found the pair and Boulter was arrested.

He pleaded guilty to a raft of charges including kidnapping, wounding with intent, injuring with intent and burglary and was sentenced to eight years and six months’ jail.

But his stint in prison did not dissaude him from offending against another woman.

In July 2019 he was jailed for a further three years and two months for stalking a woman he knew through a mutual friend.

Boulter was visiting her home and taking photos and on one day, he called the victim 300 times and left more than 100 voicemail messages.

Nathan Boulter appearing at the Auckland District Court after the Great Barrier Island kidnapping. Photo / NZPA

When he was in custody for that offending, Boulter’s menacing behaviour continued.

He told a Corrections officer that he was going to “go back to Invercargill to strangle his ex-partner” and that “once he has strangled her he can get on with his life”.

The officer tried to dissuade Boulter but he re-emphasised his intentions at least three times.

Boulter was convicted on seven charges of threatening to kill, contravening a protection order, assault with intent to injure, and causing harm by digital communication.

He was jailed in July 2020 and has been refused parole several times since.

Last year the board said it had serious concerns about Boulter’s risk level due to an apparent lack of “emotional stability and insight” into his offending.

Judge David Mather said the concerns were exemplified by a meeting Boulter had with a psychologist - which had to be terminated because of his threatening demeanour.

“The psychologist identified an array of unmet treatment needs,” Judge Mather said.

“Mr Boulter accepted that he has a range of deep-seated issues which need to be addressed. He is unsure how long that will take and acknowledged the possibility that he may need to serve his entire sentence.”

Boulter’s sentence ends on April 18 this year - meaning legally he has to be released.

But if he is granted parole before then, the board can impose a number of conditions to continue to monitor and manage him in the community.

Parole Board panel convenor Judge Charles Blackie said when he was last seen, Boulter “had not engaged in any formal rehabilitative programmes but expressed a willingness to undertake individual treatment with a psychologist”.

Judge Charles Blackie. Photo / Dean Purcell

“Clearly, he needs to work with a psychologist around the nature of his index offending and also what may be appropriate accommodation for him following his ultimate release, he said.

“Today, the situation is somewhat unclear. Mr Boulter has had a number of individual sessions with a psychologist, and it is anticipated that this will continue in the immediate future.

“However, with regard to accommodation, despite extensive inquiry, no firm proposals are able to be put forward.”

Judge Blackie said three accommodation options were put to the board, including Boulter going to live under the watch of a community reintegration-focused organisation.

However, it was unlikely there would be a bed available for him before his release date.

Judge Blackie said there was “a need for a multidisciplinary team meeting” to consider all aspects relating to Boulter’s “current position”.

He asked for an “updated psychological memorandum relating to the one-to-one treatment he had undertaken so far” and a “projection of such treatment during the remainder of his sentence, and also upon release”.

“As there are a number of issues yet to be resolved, Mr Boulter remains an undue risk and therefore, for today’s purposes, parole is formally declined,” Judge Blackie said.

“He should, however, be seen again within two months, that is by the end of March 2023, in order to allow sufficient time for the multidisciplinary team meeting to be undertaken and for an appropriate report to be made available to the next board.”

Judge Blackie said Boulter would “ultimately be best served” by having “adequate wraparound support” that was available at both his approved release address and “in the outside the community”.