Quinn Patterson didn't have a firearm's licence.
But that didn't stop him using his mate's TradeMe account to get hold of 10 guns, including two AK47 style machine guns, and shooting his property manager and her daughter dead.
Patterson died in the fire that consumed his house during an armed seige with the police.
However today Michael John Hayes, the man who helped Patterson amass an arsenal of restricted guns, was sentenced to home detention for a year.
Hayes met Patterson after Patterson responded to his advertisement about killing possums in the area.
The pair ended up developing a friendship with Hayes taking his son and sister's partner to Patterson's place for target practice.
Hayes had a firearm's licence which meant he could lawfully own his 12 gauge shotgun and two .22 calibre rifles but he didn't hold the special permit required to own the semi automatic, an AK47 style machine gun and a semi-automatic shotgun. He took them anyway and all four men fired them.
Hayes left the guns and ammunition with Patterson.
Hayes also helped Patterson out with applying for a firearm's licence by writing a letter of support for Patterson.
However, Patterson had a history.
In 1983, he viciously stabbed police dog handler Bruce Howat in with a 30cm-long bowie knife.
Mr Howat managed to overpower Patterson, despite being stabbed at least eight times and losing a lot of blood.
So when Patterson applied for a firearm's licence in 2016, it was not surprsing police rejected the application.
Despite knowing Patterson did not have a firearm's licence, Hayes continued to help his friend get more guns.
One of the guns had been modified to carry a 100-round magazine. Judge John McDonald asked Hayes' lawyer Arthur Fairley why Hayes would need such a weapon.
Judge McDonald: "What's he going to do with that? He's hardly going to hunt deer with a 100-round rifle?"
Mr Fairley: "But Sir, there's no suggestion that this man was going to hunt humans with it or know anyone would ..."
Judge McDonald: "That's the only point of having these military-style semi-automatic firearms - it's to hunt humans. That's what they're designed for."
Patterson also used Hayes' account on the online auction website TradeMe to buy four shotguns, four .22 calibre rifles and two AK47 syle semi-automatics.
Judge McDonald said Hayes went into the police station to complete the required paperwork.
"Mr Patterson couldn't do that because he didn't have a license," Judge McDonald said.
"So you went in and represented to the police that you were the person purchasing the guns, whereas in fact, it was Mr Patterson. You gave your address as a place where the guns could be delivered after the auction was successful."
Patterson's last gun - a 12 gauge shotgun, was bought just eight days before the fateful visit by Wendy Campbell and her daughter Natanya.
The pair were the property managers for Patterson's Mount Tiger Road home. They visited on 26 July last year along with contractor Jeffrey Pipe who had been brought along to install smoke alarms at the home.
However after a short discussion, Patterson reached for one of his many guns. He shot 37-year-old Natanya at close range.
"He also shot at Mr Pipe, hit him, but luckily for him, he was able to get away and raise the alarm," Judge McDonald said.
Meanwhile 60-year-old Wendy had gone to the aid of her daughter. Patterson shot her at close range too. Both women died at the scene from gunshot wounds.
"The Crown are not saying, as they cannot prove, it was one of the four .22 rifles that you left at Mr Patterson's home, was the gun used by Mr Patterson to murder the Campells - they are quite unable to prove that," the judge said.
Patterson then went back inside his house.
"The police arrived, Mr Patterson refused to surrender to them. He fired at them, a rapid series of shots from a large calibre semi-automatic rifle. I will infer that it was one of the military-style rifles," Judge McDonald said.
When all efforts to get Patterson to surrender had failed, the police fired teargas cannisters into the house.
The house caught fire and Patterson died inside. A later search of the charred remains of his house revealed Patterson had 11 guns.
It didn't take the police long to catch up with Hayes. A search of his house produced four more guns.
Hayes was interviewed three times in the days following the murders. He confirmed he had had semi-automatic guns and that he had supplied them to Patterson.
"You first said that you'd given Mr Patterson six firearms for him to store because you didn't have room at your own home. I consider that explanation fanciful."
He also told the police he felt guilty and responsible for what had happened.
In sentencing, Judge McDonald took time off Hayes' sentence for his service in the army as a Sergeant and the humanitarian work he had done in Cambodia and Laos where he has helped to remove landmines.
"Mr Hayes, this has been a difficult sentencing exercise for me. On the onehand I have a man who has, for almost his entire life, served others," Judge McDonald said.
"On the other, for some reason which has never been explained to me, you've allowed yourself to be trapped by Mr Patterson, to do his bidding, to provide him with an arsenal of firearms."
The judge also took time off Hayes' sentence for his early guilty pleas.
But just how Hayes was able to access a 100-round magazine is not clear.
RNZ News also wanted to ask the police about a visit they made to Patterson's property a month before the shooting after receiving information about a shooting platform being built for target practice.
A police spokesperson said they would not be commenting before a Coroner's inquest into the Campbells' killing took place.