The Northland man who shot three people had served time for stabbing a police officer 34 years ago.
In an exclusive interview, the former constable said the 1983 attack scarred him for life and ended his police career.
Rotorua man Bruce Howat, 64, told the Herald that news of yesterday's shooting resurfaced painful memories.
Quinn Lorne Patterson, aged in his early 50s, had been living in the remote Northland home near Whangarei, up a 200m driveway, when he shot and killed property inspectors Wendy and Natanya Campbell.
He also shot contractor Jeff Pipe, who was with them but he managed to escape.
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Patterson ran a property maintenance business from the house. The three reviews on a website for New Zealand businesses were positive.
Locals described him as a little unusual but friendly enough but he was very protective of his home, had - and used - guns and didn't like to let people inside.
And few locals knew of his criminal past, dating back to when he was aged in his 20s.
The Herald understands Patterson moved to New Zealand from Canada in his late teens with his parents and siblings, and that the family had lived in the Coromandel.
On June 20, 1983, when Patterson was 21, he was at a bar on Victoria St in central Hamilton with his brother and was seen by a staffer with a 13-inch hunting knife, according to a transcript from court proceedings, Howat said.
Howat was then a 31-year-old police dog handler with two children who was living in Te Awamutu but working in Hamilton.
He stopped to speak to Patterson on a central city street because he "didn't look like he was up to much good" and he suspected him of painting grafitti.
Patterson ran off, Howat gave chase, letting his police dog Cara out of the car to help.
He was "stabbed under a tree" several times in the arm.
Howart described Patterson as "a little runt" who wore glasses.
"He was so small that after he stabbed me, I picked him up by the belt with one hand and tried to carry him back to the police station."
His left arm was slashed and he suffered severe nerve damage. He spent four days in intensive care and a further two weeks in a hospital ward.
Howat said there had been "four or five" mistrials with Patterson before he was finally convicted in 1984 and sentenced to 18 months for grievous bodily harm.
A story from the Herald archives after sentencing at the High Court at Auckland in November of that year said that Justice Vautier was "disturbed" that Patterson already had a conviction for assault with intent to injure in a separate incident.
"A blow struck at a policeman in the execution of his duties is an attack on the whole society," the judge said then.
Howat said Patterson left the country after he got out of jail on parole.
Howart's arm is still scarred and he is unable to pick anything up for longer than a few seconds.
He never returned to the police force.
"It has certainly woken up ghosts of the past, you think you are 100 per cent over something, and then this happens," Howart said.
"I suffered severe nightmares for nearly three years and it took about another four to five years to become reasonably free from them.
"My journey is the same as many victims of serious crimes - it takes a long time to get to as good a place as you are ever going to get. Don't get me wrong, I love life and get on with things, but it is always there what I went through.'
Howat hadn't heard about the incident when the Herald called on Wednesday night.
"It's the first I've heard his name since 1985.
"I walked into the Hamilton police station and said 'Why haven't you told me? I'm a victim?'."
He said officers didn't confirm the name to him as they said it was still an open investigation but that they would call him later.
"I could tell by their body language that it was him," Howat said.
They then called and "apologised profusely" but said it would take a couple of days to confirm Patterson's identity.
A police spokeswoman told the Herald that they appreciated yesterday's shooting had been a traumatic event for a wide range of people.
"Police take our obligations under the Victims' Rights Act very seriously, however this does not extend to notifying all previous victims of unrelated offending.
"To do so would be impracticable and police note in this case the offence occurred some 34 years ago."
She said police were focusing on the victims' families from yesterday's shooting.
"They have lost a mother and daughter and we will do everything we can to support them."
She said police were yet to confirm the identity of the alleged offender involved in yesterday's shooting in Whangarei.
Howat now lives in Rotorua where he runs a charitable trust which matches apprentices with suitable workplaces, called My Future Rocks.
A neighbour of Quinn, Brad Walters, said he would fire off weapons all the time, including what he believed were semi-automatic weapons.
"He was okay, he was a friendly enough guy."
Walters said Patterson was "protective" of his property.
"I turned in there one day, and he would always come out and make sure he wouldn't let you into his house - that's for sure."
Walters said he heard gunshots from the property all the time, and added Patterson wasn't a known hunter.
He said he didn't like pig hunters entering his property.
"He just shot in his back lawn by the sounds of it, you could hear it from here, you could hear it from everywhere.
"They were big guns ... we're talking automatics, semi-automatics, big calibres. They sounded like cannons, you could hear them going off with, like, 16 rounds.
"I did hear he was trying to import semi-automatics as well, it sounds like he's already got them though.
"Someone had said that they'd been stopped by Customs at the airport ... his guns."
Walters said police knew Patterson.
"One of the neighbours used to be a cop and he said, 'just be wary of him'."
He said Patterson had attended local community meetings to help with pest control.
"He was getting letters out to neighbours to make sure people knew who was who, and have a get-together, so he did come across as pretty good as long as you didn't enter into his property."
Walters said Patterson had been living in the house for a few years and believed he was renting the property.
"If you were that private, you'd think 'why would you be shooting something so f***ing loud'.
"I think he just had his own thing going on ... he was just sort of a law unto his own."
Patterson was described as "intimidating and aggressive" towards his property manager Wendy Campbell, who ran Seek n Find in Whangarei with her husband Tony Rodgers.
She had only been managing his property for a few months.
"I know there have been difficulties but I'm really not in a place to say what they are but I know she had some concerns," said Campbell's friend Julie Pepper.
Yesterday, after police discovered the bodies of the Campbells, Patterson shot at police and they returned fire, also using tear gas.
Walters said the firefight lasted about two minutes before the house "exploded".
"He just lost the plot.
"I don't know what was inside that house but he wanted to burn it. And it went up like fireworks."
Northern Advocate editor Craig Cooper said Patterson was familiar to staff and had come into the office several times before to place ads.
"It was fair to say he came across as one of those people we refer to as being a little bit unusual."
Michael Jordan, who lives about 100m away from Patterson's home, described him as a "loner".
"All I know is, the guy, that I presume is the one responsible for the shooting, has been living there for years," he said.
"I think he rented it. I don't know him that well, we used to stop and talk every so often. He kept to himself, I don't really know him that well. He's a bit of a loner really."
Jordan only ever saw one man at the property and did not believe the man had a wife or children at the home.
"He actually drove past, going to town, and he tooted and waved," Jordan said of one meeting.
"We're on a rural road, so it's not like we're in the middle of town."
Jordan said the man would probably be in his mid-50s.
"From what I know he's the one responsible but, until we hear all the facts, I wouldn't know."
A large plume above Whakaari/White Island prompted questions.