Since then Bain, who turned 52 in March, has avoided any publicity.
Seven years ago, it was rumoured he and his wife Elizabeth Davies - a primary school teacher and daughter of one of his biggest supporters during his retrial - had moved to Australia for a fresh start.
However, the couple and their children – a son born in 2014 just months after the couple wed, and daughter Arawa [named after Bain’s murdered sister] who arrived three years later – have been living at a rural property near Cambridge for some time.
Bain now goes by the name Liam Davies and his wife teaches at a nearby school.
He changed his name to William Cullen Davies in 2017, the same year his daughter was born, and it is understood he changed it a second time after the first moniker was made public.
The Herald visited the Davies’ property yesterday.
After some time Bain answered the door. He confirmed his new name and asked the reporter not to come too close.
“I’m very, very sick,” he said, wearing a surgical mask across his face.
When asked if he wanted to speak about the anniversary of the deaths of his parents and siblings, Bain quickly shut the door.
His home is a new build - four bedrooms - sitting at the front of a rural block.
A large black dog was roaming around the yard, a warning to “beware” the animal on the gate.
All of the curtains at the front of the house were drawn but the garage door was open, laundry drying on a rack in the sun and a child’s plastic bike.
Despite reports he had moved across the ditch to Australia, he has been here all along.
“He had one short holiday there on the Gold Coast with his wife, but he never contemplated living there and never went there at all,” long-time supporter Joe Karam told The Front Page.
Karam said David and his family are doing well, even as the 30th anniversary approached.
“They eventually shifted to where they now live. His wife has a very good job and is highly respected, and they’ve built a great life for themselves,” Karam said.
“They’ve got two children who are doing exceptionally well, and they’ve got a great support network in the community where they are.”
While Bain himself would not comment on his family’s grisly demise, his uncle – Robin’s brother – did speak to the Herald.
“The matter’s still fresh in our minds,” Michael Bain said earlier.
“We are all still carefully treasuring the memories of each of those who were lost on that terrible day.
“Over the last 30 years, Robin and Margaret should have been able to enjoy seeing Arawa and Laniet and Stephen mature into the fine adults they would undoubtedly have become.
“They would have developed their own careers and hopefully had families of their own.
“The tragedy is that they were all denied that opportunity.”
When Robin, Margaret, David, Arawa, Laniet and Stephen Bain went to bed on the night of Sunday, June 19, 1994 they did so as members of an ordinary albeit non-conventional Kiwi family.
They all had plans for the next day: work, university, school, errands.
David, 22, was out the door about 6am to do his morning newspaper delivery - the family dog Casey in toe.
At 7.09am David called 111 and told the operator: “They’re all dead”.
By 7.28am the first police officers arrived at 65 Every St.
Within hours the Bain family were at the centre of what would become New Zealand’s most high-profile family mass murder.
Initially, police believed it was a case of murder-suicide and Robin was the man responsible - that he had spiralled into a deep depression and “snapped”.
They surmised Robin had come into the house while David was out delivering the Otago Daily Times, ended four lives then went to the living room where the communal computer sat and typed a suicide note.
“Sorry, you are the only one who deserved to stay,” it read.
Then, they theorised, Robin put the semi-automatic .22 Winchester rifle to his left temple and pulled the trigger for the last time.
Soon after his body crumpled to the floor, David arrived home, unwittingly stumbling into the horrendous crime scene.
But each day, more forensic evidence was found in the house that pointed away from Robin to his surviving son.
David’s bloody fingerprints were lifted from the rifle.
His partial palm print - also in blood - smudged onto the washing machine.
That was suspicious to investigators because David said he’d thrown his clothes in the wash before finding his family members dead.
He could not explain how the bloody prints got where they were.
And then there was the 111 call. Bain had told the operator, repeatedly: “They’re all dead”, but later told police he’d seen only his mother and father.
On the Wednesday, police found a bloodied pair of his gloves under Stephen’s bed.
On Thursday, a lens from a pair of David’s glasses was found in the teen’s room.
The other lens and frame were in David’s room on a chair.
Police believed the glasses were broken as Stephen struggled with his oldest sibling, as he was strangled with his own t-shirt and before the fatal gunshot.
When it was over, they said, David had collected the frame and one lens, but could not find the other in Stephen’s messy space.
On Friday morning – as David was finalising plans for a combined funeral for his parents and siblings the next day – police requested another interview with him.
At 1.46pm that day, he was charged with all five murders.
“Do you have anything to say?” police asked.
“No, I’m not guilty,” David said.
After a high-profile trial, a jury found him guilty.
He maintained his innocence and fought for decades for a retrial, which finally went ahead in 2009.
A second jury acquitted Bain, finding him not guilty of the five murders.
Carolyne Meng-Yee is an Auckland-based investigative journalist. She worked for the Herald on Sunday in 2007 and joined the Herald in 2016. She was previously a commissioner at TVNZ and an award-winning current affairs producer for 60 Minutes, 20/20 and Sunday.
Anna Leask is a Christchurch-based reporter who covers national crime and justice. She joined the Herald in 2008 and has worked as a journalist for 18 years with a particular focus on family violence, child abuse, sexual violence, homicides, mental health and youth crime. She writes, hosts and produces the award-winning podcast A Moment In Crime, released monthly on nzherald.co.nz