Police have confirmed they visited the scene of Wednesday's fatal shooting in Northland last month after concerns about an illegal structure built on the property.

In a statement issued this afternoon, police said an officer offered to visit the property and was told that the structure was a platform to be used for target practice.

After discussion with Quinn Patterson, and with no other relevant information the officer was aware of about Patterson, or activity at the property, he was satisfied it was a tenancy matter that required no further action by police.

This visit to the property forms part of the ongoing investigation into what was known about Patterson's background.

The statement added: "While we understand the public's need for answers, Police is still piecing together everything that happened leading up to the events on Wednesday 26 July."

Fire inspectors and forensic staff are continuing to comb through the burnt-out house of Quinn Patterson, while his only surviving victim from Wednesday's shootings is interviewed by detectives at his waterfront property.

Patterson's suspected badly burned remains have been discovered at the rental home on Mount Tiger Rd, just north of Whangarei, with police adding last night that what may be a firearm was also found next to the 55-year-old's body.

Meanwhile, Jeff Pipe, the only surviving victim from the trio who visited the house to conduct a routine property inspection, has returned to his Onerahi home.

He continues to recover from gunshot wounds to his back and shoulder after escaping Patterson's fire by driving down the narrow and windy road in his maroon Suzuki jeep to the saftey of armed police.

Today, detectives, who have begun what will become a lengthy and "meticulous investigation", were at Pipe's home as they determine the catalyst for the killings of Wendy Campbell and her daughter Natanya.

Pipe's family, some of whom are believed to have arrived from Christchurch, have been by his side.

Police were seemingly unaware of the cache of arms Patterson had procured, and said last night, exactly what firearms and other weapons Patterson had will only become apparent once the detailed scene examination is completed.

However, police did confirm to the Herald yesterday that Patterson did not hold a firearms licence.

Despite this he was still able to reportedly build an arsenal of grenades, shotguns, rifles and handguns.

"How he came to acquire these firearms is clearly a concern, and an important focus of the investigation," police said.

Neither police nor Customs officials will discuss how Patterson may have established his armoury, but neighbours have alleged to the Herald that he was importing them from overseas.

Several neighbours have also told the Herald Patterson would regularly test his weapons in his backyard. 

"I appreciate there are many questions being asked about this tragedy. These issues all form part of the meticulous investigation which is ongoing," Superintendent Russell Le Prou, the Northland District Commander, said.

"It is very important that we fully understand what led to the events of Wednesday, including what was known about Patterson."

Back at the crime scene, several fire investigators, who were at the property again early this morning will continue to establish what started the fire which destroyed the house.

Forensic staff will also spend the weekend conducting a detailed search of what remains of the property.

The home went up in flames on Wednesday afternoon, after a firefight between police and Patterson as negotiations with gunman failed.

The Armed Offenders Squad heroically tried to reach both Wendy and Natanya by forming a human shield around medically trained officers, but were pinned down by Patterson and sought cover, unable to save the pair.

"We will work tirelessly to ensure we get answers to the questions which are being asked, and identify any steps needed to prevent a tragedy like this occurring again," Le Prou said.

"It is at times like this that our community really shows its strength."