Police were told a target range had been set up at the home of a gunman who would go on to kill two women in rural Whangarei, but wrote it off as a "tenancy matter".
Shooter Quinn Patterson, 55, was visited by an officer last month following complaints he had built an illegal structure on the property he was renting on Mount Tiger Road, police confirmed on Saturday.
"The officer offered to visit the property and was told that the structure was a platform to be used for target practice," police said.
“After discussion with 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."
On Wednesday morning, Mr Patterson shot and killed Wendy Campbell, 60, and her daughter, Natanya, 37, while they were conducting a property inspection of the home.
Contractor Jeff Pipe was also shot and wounded and has been recovering in Whangarei Hospital.
- Whangarei shooting details leading up to tragic shooting show reclusive man in decline
- Patterson victim breaks down in emotional interview
- Police had no idea gunman had stash of firearms
- Two women dead in Whangarei Heads shooting
The house Mr Patterson rented went up in flames during a subsequent shoot-out with police, and his body was found in the rubble days later.
Police say Mr Patterson was in possession of multiple guns, but had no firearms licence.
Investigators were on Saturday still trying to work out the cause of the blaze.
Police hope to finish work at the scene over the weekend.
Mr Patterson's body was removed from the site on Friday and a post-mortem examination is now being conducted.
The two women's bodies were removed on Thursday and have been returned to their families, police said.
Mr Patterson served 18 months in prison for stabbing a police dog handler Bruce Howat multiple times with a hunting knife in 1983.