Prison is a familiar place for 36-year-old Nathan Boulter, who this week pleaded guilty in the High Court at Christchurch to murder, a frenzied attack outside the victim’s home which was witnessed by her children.
Five years before the July killing, Boulter was standing in the dock in the Invercargill District Court, where he was jailed for nearly two and a-half years for strikingly similar obsessive behaviour, only without the catastrophic climax.
Just three months into that sentence, the Otago Corrections Facility inmate was approached by a Corrections officer because he had covered the CCTV camera lens in his cell.
The subsequent conversation was so chilling the "vastly experienced" officer immediately reported it.
He asked Boulter what he planned to do when he was released. The prisoner replied he was returning to Invercargill to strangle his "ex-partner".
Once he had done that, he could "get on with his life", Boulter said.
In the following days, Boulter wrote a letter to the woman — in breach of a protection order — seeking to rekindle their relationship.
But when he appeared before the Dunedin District Court over those incidents, the victim’s statement provided greater clarity.
She said there was no relationship to speak of; she had only met Boulter because she was a friend of his sister, and he had become "obsessed" with her.
The victim described the escalation in the man’s stalking behaviour.
He would drive past her home or workplace, sit outside and send her photos of the cars that were parked outside her house.
She told the court she had taken to living with her curtains drawn because of her fear.
On one particular day he called her 300 times and left 100 voicemail messages.
It was doubly terrifying for the victim given Boulter’s history of following through on his threats.
In 2012, he appeared in the High Court at Auckland, where he was sentenced to eight and a-half years’ imprisonment.
The story was similar.
A brief relationship in Southland led to the emergence of Boulter’s violent and overbearing tendencies.
When he was charged, the victim fled more than 1200km to Great Barrier Island, prompting what Justice Paul Heath called "a preconceived plan to travel almost the full length of this country".
After getting the ferry from Auckland under a fake name, Boulter trekked more than 8km across the island and hid under the woman’s bed, eventually emerging to attack her and a man who was with her.
While the male victim was unconscious with a fractured skull, Boulter dragged his ex around the island’s isolated areas, subjecting her to a 38-hour ordeal until his eventual arrest.
At his sentencing, Justice Heath opted not to impose a minimum non-parole period as "an incentive to do what you can to rid yourself of these demons before you are released from prison".
But Boulter never did.
Thirteen years after the judge uttered those words, he hid behind a tree in the Christchurch suburb of Parklands.
Boulter was waiting for the woman, whom he had been seeing for only a few weeks.
Her name remains suppressed.
In the fortnight beforehand he had made 581 calls to her phone, which she had tried to ignore, and he had sent her several overtly threatening messages.
"Your lack of human compassion and empathy will be the death of you one day soon," one said, nine days before the brutal killing.
When the victim returned to her home, Boulter — armed with a 19cm pig-sticker knife he had bought the previous day — launched his attack.
As he inflicted the 55 wounds, the woman’s children fled inside the house.
Boulter later left the knife in the home of strangers nearby, called his stepfather, then 111.
He told police: "I just killed her now. I stabbed her to death, I f..... up, bro. I need you guys to come get me. I just killed her, bro."
Boulter’s case will be called in court again next month for a sentencing date to be set.
Obsession
Dec 2010: Boulter is charged with domestic assault and bailed by the Invercargill District Court.
Jan 2011: He pursues his victim to Great Barrier Island, where he kidnaps her and subjects her to 38 hours of violence.
Jun 2012: Boulter is jailed for eight and a-half years.
Sept 2016: He tells the Parole Board his crimes come from "a feeling of low self-worth and a fear that people are going to leave him". He is declined early release.
2018/2019 (date unconfirmed): Boulter is released from prison.
Jul 2020: Locked up again for 29 months for extensive stalking and threats against another Southland woman.
Oct 2020: While at the Otago Corrections Facility Boulter tells a Corrections officer of how he plans to go back to Invercargill and kill his victim. Nine months are added to his jail term.
Sept 2021-Jan 2023: Parole is repeatedly declined. One report "raises serious concerns around [his] behaviour and risks"; an interview with a psychologist is terminated when Boulter makes threats.
Mar 2023: Boulter is granted parole weeks before the expiry of his prison term. Puts his obsessive behaviour down to his mental health issues and substance abuse.
Jul 7, 2025: He is sentenced to six weeks’ imprisonment for threatening and riotous behaviour over a stoush in a Riverton shop, Stuff reports.
Jul 23, 2025: Boulter murders a Christchurch woman he had only known for a matter of weeks.
