David Bain was "shocked to the core" to hear his groomsman had committed a second murder.
Paul Wilson, 55, also known as Paul Tainui, has pleaded guilty to raping and murdering Christchurch 27-year-old Nicole Tuxford in Merivale last year.
He raped and murdered 21-year-old West Coast woman, Kimberly Schroder, in 1994.
Wilson met Bain in jail and was groomsman at Bain's 2014 wedding.
Joe Karam, long-time advocate for Bain, says Bain is distressed Wilson inflicted such terrible disaster on the victim and her family.
He says Bain thought his friend was managing life well and there was no indication he wasn't.
Wilson lay in wait for eight hours before 27-year-old Nicole Marie Tuxford arrived back in her Merivale home in April last year.
Wilson pleaded guilty to sexual violation in the High Court in Christchurch this morning.
He had earlier pleaded guilty to the life coach's murder.
Justice Cameron Mander has indicated a sentence date of March 28.
The shocking news that Wilson committed a second murder in Christchurch in April last year – 24 years after he murdered former girlfriend Kimberly Schroder in Hokitika – was too much for Schroder's father.
Gary James Schroder, 67, died in a suspected suicide just hours after Wilson made his first court appearance on April 10 last year.
"Paul Wilson now has the blood of two young ladies on his hands. And also the blood of my dearly beloved [relative]," one family member told the Herald at the time.
Wilson was convicted and jailed in 1995 for the rape and murder of Kimberly Jean Schroder in Hokitika the previous May.
A 31-year-old sickness beneficiary at the time, Wilson visited Schroder's flat and tied up her male flatmate.
When his girlfriend came home, he cut her hands during a confrontation, before cutting off her jeans and raping her.
He then stabbed her in the neck after she made comments about relationships with other men.
Wilson was sentenced to 15 years non-parole, though on appeal that was reduced to 13 years.
His parole was granted at his fifth time of asking in December 2010, with his behaviour described as "exemplary and faultless".
Wilson was released in January 2011 into a residential programme that included at least one year of intensive therapy.
His release conditions also permanently banned him from visiting the West Coast or contacting the Schroder family, and he is subject to the "standard conditions" of parole for life, which includes recall to prison if he is deemed an "undue risk to the safety of the community".
Wilson has spent the past few years living and working in Christchurch.
He had been living in a tidy red-brick townhouse in the Aranui area of the city.
He left around 6am every weekday for his job at a scrap metal merchants on the other side of Christchurch.
His 27-year-old victim Nicole 'Nicky' Marie Tuxford had just embarked on a new career as a life coach and spiritual guide when she was killed at her home in the upmarket Christchurch suburb of Merivale, near Hagley Park, on April 7 last year.
Tuxford had been training for two years with the Phoenix Light Foundation to become a life coach.
Wilson was described as a model neighbour, keeping his place tidy and always stopping to chat with his elderly residents.
"I'm very upset by this," one woman said.
"I liked [the man]. He was always friendly, chatty. He was also a very private person."
Another neighbour said Wilson worked long hours but would always stop and say hello.
"It's very distressing actually," she said.
They say life appeared to have been going well for Wilson.
He had a solid job, recently bought a silver Audi, which his neighbours all thought was "a bit flash".
But they didn't know anything about where he'd come from – or his dark past.
He drank at the nearby McKenzies Hotel on Pages Rd, where was "just another local".
It's understood that Wilson, armed with a knife, broke into Tuxford's house some time on the morning of April 7.
The crime scene closely mirrored that of the horrific Hokitika murder years earlier, the Herald has been told.
Fleeing in Tuxford's $2000 Toyota Corolla, Wilson was involved in a minor traffic accident.
Wilson told police there were knives in the boot of the car, saying he needed them for his job.
Canterbury District Commander Superintendent John Price said two knives were secured in the vehicle's boot and police retained the keys so he did not have access to them.
Price said the officers involved had been deeply impacted by the tragic circumstances.
"There is no certainty however that anything could have made a difference to this tragic outcome given the specific circumstances involved that night."
Hours later, when the Exeter St bloodbath was discovered, the small prang suddenly took on a new meaning.
Police officers soon tracked down Wilson. He was arrested shortly after and charged the next day.
News of his arrest soon filtered over the Southern Alps – and back to the Schroder family whose lives he destroyed all those years ago.
It was all too much for Gary Schroder.
David Bain's groomsman
When David Bain wed primary school teacher Liz Davies at a winery outside Christchurch in January 2014, Wilson was his groomsman.
The killer was part of a three-man bridal party, which also included long-term Bain champion Joe Karam's sons Matthew and Richard.
Bain and Wilson met while working in the prison kitchen, a former inmate who shared a cell with Bain said.
Nancy Schroder, the mother of Wilson's first victim, told the Herald in January 2014 that it made her "bloody sick" to learn the killer was out celebrating while the family continued to grieve.
The family had strongly opposed Wilson's parole and doubted his remorse.
"I heard they had shared a cell ... and now he's out celebrating. The murdering bastard. It makes you bloody sick."
Speaking to the Herald at the time, Joe Karam said Wilson was Bain's best and oldest friend.
The pair were two of the longest-serving inmates in their section of the prison and, though other inmates came and went, the two remained close.
"They sort of naturally became ... very close friends. The single person he [Bain] has spent the most time with over the past 18 years is Paul Wilson."
Since his 2011 release, Wilson had reintegrated himself into society, Karam said at the time.
"He's done tremendous work to rehabilitate himself. He's got a job and qualifications."