The Independent Police Conduct Authority has sharply criticised the tactics used by police during the armed siege near Kawerau in Bay of Plenty in March 2016.
Four police officers were shot by Rhys Warren after he fired at a police cannabis spotting aircraft, prompting an Armed Offender Squad response, and subsequent raid.
Warren surrendered after the overnight siege, and was later convicted of two charges of attempted murder, three counts of using a firearm against a law enforcement officer and one count of wounding with intent to cause grievous bodily harm. He was sentenced to preventative detention.
A full report into the incident, which took place on March 9 and 10, 2016 at two properties on Onepu Spring Road, was released today.
On March 9 2016 about 10.30am, Warren fired shots at a spotter plane conducting a cannabis removal operation near his house.
One officer was already on the property looking for plants, and was among a plot of cannabis plants hidden in a copse of blackberry bushes when he believes he was also shot at by Warren.
The officer fled and the Armed Offenders Squad was called in - they set up a cordon by about 1pm and police used a loud hailer to repeatedly ask Warren to surrender - he did not respond.
Police obtained the landline and mobile phone numbers for the property and Warren, and attempted numerous times to call him - he appeared to hang up on them four times, before letting the phone ring without answering.
Officers used a ballistic shield to make their way around the house, smashing windows and pulling out the net curtains to improve visibility, all the while calling out to Warren and urging him to surrender.
The broken glass now inside the property meant the use of police dogs was difficult, as the broken glass could potentially injure their feet, but a dog handler who eventually entered the property decided he could carry his dog over the glass and employ it if necessary.
The use of tear gas was also decided against, as the scene commander did not consider it justified due to uncertainty as to who was inside the property.
OFFICER FELL 'STRAIGHT BACK LIKE A KAURI TREE' AS HE WAS SHOT
AOS members entered the house about 3.30pm and Warren was waiting in a bedroom at the end of a hallway.
He fired three shots, hitting three officers and badly wounding them.
One of the officers told the IPCA he felt the "hair on the back of [his] neck" stand up just before Warren opened fire.
The dog handler who entered the house was hit in the face by shrapnel from the scope of a rifle which had been shattered by one of Warren's shots.
He fell "straight back like a kauri tree" with "blood all over his face", according to the account of another officer, and received a serious brain injury requiring surgery and extensive rehabilitation.
Another felt a "punch" as he was hit in the left knee by shrapnel from a wooden cabinet - he later underwent surgery to remove embedded fragments.
The AOS members reported hearing "screaming" and "groaning" as they returned fire, forcing Warren to take cover, and the three wounded officers were dragged to safety.
Police fired a total of 46 shots back at Warren - none hit him.
Later that day about 5pm, Warren also shot another police officer who was stationed at the cordon.
He remained inside the house until 9am the next day, when he gave himself up, much to the relief of worried whanau who had gathered at the scene.
ENTRY PLAN WAS "ILL-CONSIDERED AND WRONG", IPCA SAYS
"The tactical decision-making and control and command exercised by Police in response to shots fired near Kawerau on 9 March 2016 was highly flawed and placed Police officers at risk," the report reads.
"The decision to enter 158 was ill-considered and wrong.
"The Authority has found that the AOS officers should never have entered the Warren family's house, and that there was poor general understanding amongst officers at all levels about how control and command should have operated during different phases of the Police response.
"The lack of proper oversight was a strong contributing factor to the flawed tactical decisions."
The IPCA said two police officers did not follow correct procedure before entering the two properties, as they failed to notify the communications centre and also failed to carry out a risk assessment.
The use of a cordon in this situation was described as "aggressive" by the IPCA, and that "greater consideration should have been given to a less risky deployment tactic".
The IPCA said police were justified in shooting back at Warren during the incident and that good aftercare was given to the wounded officers.
POLICE ACCEPT FINDINGS - BUT 'THE PERSON RESPONSIBLE FOR SHOOTING OUR STAFF WAS RHYS WARREN'
Police say they accept the criticism in the report and have taken steps to remedy their shortcomings.
Assistant Commissioner Districts Bill Searle said in a statement that police conducted their own internal investigation into the incident, and that their findings were "consistent" with those of the IPCA.
"As a result Police have made a number of changes at both district and national level," Searle said.
One such change is ensuring all police dogs are issued protective boots for situations where there is a possibility their feet will be injured.
Police are also trialling a dog-mounted camera system which can provide a remote view to officers outside of a premises.
"Ultimately, incidents such as Operation Pencarrow are often complex and dynamic," Searle said.
"Circumstances can and do change very quickly and decisions have to be made based on the information available to officers at the time.
"The safety of our staff and members of the public is a strategic and operational priority for Police ... the fact four officers were injured in this incident is of great concern to us.
"The lessons learnt from our own review and the IPCA report into Operation Pencarrow have been carefully considered to ensure we operate in the safest and most effective way to protect both our staff and the community.
"Despite the issues raised by the IPCA, we note that the person responsible for shooting our staff was Rhys Warren."