The Independent Police Conduct Authority has found that three police officers on a search boat did not do all they should have to rescue a man once he was found.
On 27 April, 2018 the 36-year-old man named as Mr X in the report had been tracked to the Waikato River in Hamilton after a violent assault on his partner.
Indications were that the man had gone into the river.
The Waikato police boat and the Eagle helicopter were called to assist in the search.
An acting inspector managing the search told the officers not to bring the man on board without first making a plan for doing so.
The authority says they took this to mean their role was limited to assisting in the search and did not plan to rescue the man.
In the early hours of the morning the Eagle crew spotted the man in the water, alongside a steep cliff, with no way out of the river.
The officer skippering the boat took the boat to a position about 15 metres downstream from Mr X. This was too far away to deploy rescue equipment, but he kept the distance because of the danger they believed the man presented.
Eagle footage showed that Mr X began moving towards the police boat but was caught in a strong current which pulled him into an eddy. Mr X disappeared underneath the water and was not seen alive again.
The Authority found the officers were not adequately trained or sufficiently experienced to manage a rescue operation. It found they were overly focused on earlier warnings and instructions from senior officers, instead of making their own risk assessments and planning for the possibility of finding Mr X in the water.
The skipper did not show the leadership needed as the search operation developed into a rescue and placed the boat in a position that made retrieving him from the water impossible.
Authority chair Judge Colin Doherty said: "While the officers were not under a legal duty to protect Mr X from injury when he disappeared underwater, a moral obligation to help him arose from the nature of the operation. Officers did nothing to help him when it was most needed."
Staff operating in 'challenging and dangerous environment'
The police have acknowledged the IPCA findings.
Assistant Commissioner Districts Lauana Sue Schwalger said staff responding to the search had reason to believe the man may have had a firearm.
She said that while the man was located in the water by the Eagle helicopter, staff on the water were unable to reach him and sadly he drowned before police were able to intervene when he was pulled into a strong current.
''The situation that our staff found themselves in demonstrates the complexities and challenges of policing."
''The public have high expectations of police officers and in this situation our staff were operating in a very challenging and dangerous environment.''
Schwalger said conditions were challenging for staff given how dark it was and noise from the boat and the helicopter above meant they could not hear the man in the water. Nor were they aware that he was in any difficulty.
''Our staff made decisions with the best intentions in a high pressure environment on the day, however, as shown in this instance the situation can change quickly.''
She said this was an outcome no one wanted and police offer their sympathies to the friends and whānau of the man who sadly died.
"Police accept that there are learnings to take from what was a complex and challenging situation.''
She said there has been a review of the water rescue training processes in Waikato.