Alo Ngata died from asphyxia after his spithood was applied wrongly during a violent struggle with arresting officers in July 2018.
Police have been censured over the death of a man tasered four times, pepper-sprayed twice and later left in a cell wearing a spit hood.
The criticism comes in an Independent Police Conduct Authority report released today which states there were "multiple failures" by officers involved in Alo Ngata's arrest.
Ngata had "strongly resisted" arrest, and had been tasered four times, pepper-sprayed twice, and restrained with handcuffs, leg restraints and a spit hood before being taken to the Auckland District Custody Unit.
Police have acknowledged that a spit hood was wrongly applied during the arrest of a man who soon after died of asphyxia.
Superintendent Karyn Malthus, Auckland City District Commander, said the incident involving Ngata in July 2018 was "extremely difficult" for attending officers on the night.
Unfortunately, the spit hood was not applied correctly and this was not noticed by successive police staff.
The IPCA's report found these uses of force were appropriate, necessary and proportionate to the level of resistance Ngata was displaying at the time.
Officers were unaware the spit hood was incorrectly applied as they drove him back to Auckland police station where they proceeded to remove the Taser probes.
Because the spit hood had been applied incorrectly, they were unable to see that he might have been having difficulty breathing.
As Ngata was still moving and making unintelligible noises, the officers thought he was continuing to resist them, and took no steps to check on his welfare.
After removing the restraints, the officers left Ngata alone and motionless on the floor of the cell face down.
The spit hood was left in place still covering his entire face. Although he was supposed to be under continuous observation, it is clear from the CCTV footage that officers were not constantly watching him.
After a couple of minutes, a custody officer realised Ngata appeared to have lost consciousness, but it took officers between one and two minutes to re-enter the cell. They then attempted to resuscitate him and called an ambulance, the IPCA report stated.
Police acknowledged the IPCA's concern about the role of custody staff at the time, and accepted that the supervisor should have focused attention on elements such as the spit hood and constant monitoring, however upon realising that Ngata was in medical distress police acted appropriately, she said.
Following the incident, police launched its own critical incident investigation which examined criminal culpability.
After consideration of expert evidence and independent legal advice, it was determined that legal causation for Ngata's death was not established and on that basis no person was criminally culpable, she said.
Malthus emphasised the fact the pathologist was unable to determine whether the use of a spit hood in this case had any causal effect on his death.
"Causal effect" in this incident meant causation in the context of assessment of any criminal culpability.
She said the IPCA examined the findings of its investigation and noted the pathologist's finding that removing the spit hood might not have changed the outcome.
"The conduct of the employees involved in the incident was assessed. It was considered that there was no behaviour contrary to police's code of conduct that required an employment investigation.
"I acknowledge that the death of Mr Ngata was a tragic event. I would also like to acknowledge the extreme danger to all staff involved in this incident.
"Their intent was to bring a violent offender under control and to ensure the safety of our community. They were all working in extremely difficult circumstances."
Police had noted "a number of lessons learned around the handling of highly agitated people in custody", in light of the incident, she said.