Shocking details of how a Northland property manager and her daughter were fatally shot by crazed gunman Quinn Patterson have emerged nearly a year after the tragedy in Whangārei.

The details are contained in a police summary of facts relating to Whangārei salesman Michael John Hayes who has pleaded guilty to supplying various firearms to Patterson
- including the suspected murder weapon - between March and May last year.

Hayes, 61, admitted in the Whangārei District Court on May 4 three charges of unlawful possession of military style semi-automatic weapon and three of supplying military style automatic weapon to person who did not hold a permit. Patterson did not have a firearms licence.

The maximum penalty for the charges are three years in jail or $4000 fine.

Hayes also pleaded guilty to three further charges of supplying firearm to unlicensed person which carries a $1000 fine or a three-month prison term and will be sentenced on Friday.

Patterson shot dead Wendy Campbell and her daughter Natanya Campbell during a property inspection on July 26 last year.

They were accompanied by contractor, Jeffrey Pipe, who intended to install smoke alarms in the Mt Tiger Rd house Patterson rented.

After initial discussion between the visitors and Patterson at the front door, he fired shots at Natanya Campbell from close range.

He then fired at Hall who suffered injuries to his shoulder and back but was able to get into his vehicle and escape.

Patterson then approached Wendy Campbell who had gone to her daughter's assistance and shot her at close range several times. Both women died at the scene.

Analysis of cartridges ejected by the weapon Patterson used in the shootings showed it was a .22 calibre weapon, with a similar firing pin as a Gervarm .22 calibre rifle.

Following four hours of negotiating with Patterson, police fired tear gas into the house and Patterson fired a rapid series of rounds from a large semi-automatic weapon. A fire erupted that destroyed the house and Patterson was found inside dead.

Police recovered 11 firearms from Patterson's house and a further four from a property Hayes lived in.

It can now be revealed that Patterson bought 10 firearms on his Trade Me account using Hayes' name firearms licence between September 9, 2016 and July 18, 2017.

They included four shotguns, four .22 calibre rifles and two 7.62 calibre AK-47 type weapons.

Hayes met the gunman around 2013 or 2014 when Patterson responded to a letter drop by Hayes seeking properties on which to trap possums.

In 2016, Hayes agreed to be a referee for Patterson and provided a letter of support after the latter indicated he would apply for a firearms licence.

That application was rejected by police in September 2016 on the grounds Patterson was not a fit and proper person to hold a firearms licence.

Between March 1 and May 1, 2017 Hayes went to Patterson's house and took with him military style semi-automatic firearms and ammunition including two Gervarm.22 calibre rifles and one Mossberg 12-gauge shotgun.

Hayes held a firearms licence from June 17, 2014 to August 8, 2017 when a revocation notice was served on him. However, he did not hold the appropriate licence endorsement to possess any military style semi-automatic firearms at the time he had the weapons and supplied them to Patterson.

Hayes, his son, his sister's partner and Patterson shot targets with the firearms at Patterson's property.

During three police interviews in July and August last year, Hayes admitted supplying the firearms to Patterson and to others. He initially claimed he left the firearms at Patterson's house as he had insufficient storage at his property.

Hayes said he knew neither Patterson nor others who used the guns held a firearms licence or an endorsement to obtain or possess military style semi-automatic firearms.

He also claimed Patterson had purchased the firearms for him to be returned to the gunman when, and if, the Mt Tiger resident had obtained a firearms licence.

Hayes said he felt guilty and responsible for what occurred.