He was seen running towards a park bordering the Waikato River at about 11.08pm. A police dog handler tracked the man to the river's edge, where the dog indicated he had gone into the water.
The Waikato police boat and Eagle helicopter were called to assist in the search.
The police boat was crewed by three officers. Two had been trained to operate the police boat while a Fire and Emergency New Zealand officer joined them on board, operating a thermal imaging camera to assist with night vision.
The Acting Inspector managing the search told the boat crew not to bring the man on board without first making a plan for doing so.
READ MORE:
• Police search Waikato River for missing man wanted in relation to serious assault
• Body recovered from Waikato River after search for wanted man
• Police seek Hamilton man seen approaching young girl
• Police discover body of missing Waikato DHB mental health inpatient
The officers on the boat took this to mean their role was limited to assisting with the search for him, and did not plan for rescuing him from the water if needed.
LAST MINUTE ALIVE
The dramatic scenes of the man's last minute alive were revealed in the report.
It states when officers on the bank told him he was under arrest, he replied "yeah, just pick me up", but the boat crew said they did not hear that.
An officer then told him to go back to the riverbank, while another officer radioed that the boat would keep its spotlight on him.
At 12.28am, another officer radioed the boat crew saying, "yeah boat, just keep an eye on him, he's coming out".
An officer on the boat immediately responded, "yeah, affirm, we're not getting him on board though with a firearm." Eagle also radioed that Mr X was swimming out into the middle of the river.
In footage obtained by the Eagle chopper, it showed him continuing to move towards the boat, but he appears to stop after travelling about 6m towards the boat.
Throughout, officers on the boat can be seen standing and watching him swim.
Seconds later, the man's direction of movement changes and he appears to be being pulled by the current back and towards the centre of the river.
His arms couldn't be seen above the water, suggesting he wasn't deliberately swimming in a different direction.
A few seconds later an officer yells into the radio, "boat, move up to him now! He's going under!".
In the minute which had passed since the man left the riverbank, he was swept away with footage suggesting the current pulled him into a strong eddy, which dragged him
beneath the surface.
He was last seen on Eagle footage at 12.29.51am.
Immediately after he disappeared an officer puts an oar into the water, described by the authority as a "futile action" given that the man had already disappeared.
"DID NOTHING TO HELP HIM"
The authority found the officers were not adequately trained or sufficiently experienced to manage a rescue operation. It found the officers on the boat 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 the man 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 the man from the water impossible."
Judge Doherty added that while the officers were not under a legal duty to protect the man 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."
Police have not released the man's name.
"WE THOUGHT HE HAD A GUN"
Assistant Commissioner Districts Lauano Sue Schwalger described the incident as "challenging" and that police on duty at the time believed the man had a gun and were unaware that he was in trouble.
"Staff responding to the search had reason to believe the man may have had a firearm.
"While the man was located in the water by the Eagle helicopter, staff on the water were unable to reach the man and sadly the man 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 police were "operating in a very challenging and dangerous environment".
"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."
A review of water rescue training processes in Waikato had since been carried out.