A police officer used excessive force which was "contrary to law" against a 15-year-old boy who was held against a cell wall by his throat at the Taupo Police station, the Independent Police Conduct Authority (IPCA) says.
In the incident around 10:30pm on November 21, 2014, police were told of two boys acting suspiciously south of Taupo who had subsequently got a ride from a passing vehicle.
Concerned about their safety, two officers stopped the vehicle and decided to take them home.
One was taken home, but the other refused to give his address to police so was taken back to the station to find out where he lived.
On their way back to the station, police found the boy had a can of pre-mix alcohol which they thought could have been used as a weapon.
"Officer A stopped the patrol car and held the boy down on the backseat in order to remove the can, search and handcuff him due to safety concerns for both officers," the report, released today, says.
Once at the station, the boy became upset when he was told he'd be going back to his mum's home, saying he didn't want to go.
He went into an empty police cell and was followed by Officer A, who "grabbed the boy as he was sitting on a bench and held him against the cell wall by his throat".
The teenager told the IPCA his feet were off the ground for 15 seconds and could not say anything because he was being choked.
"He said he thought he was going to die," the report says.
Officer A said when the teenager was in the cell he "postured like he was going to kick" him and was going to spit at him.
The incident was seen by Officer B who thought the use of force was excessive and reported it to their supervisor.
"This degree of force was not justified in the circumstances. Officer A's actions escalated the situation rather than resolved it," IPCA chair Sir David Carruthers says.
The report found the officers were justified in taking the boy back to the station to find out his address and also to take the alcohol, search and handcuff him in the back of the patrol car.
It was revealed he had been in the care of Child, Youth and Family until two days before the incident before being returned to his mother. Bay of Plenty police say they accept the report's findings.
Taupo Area Commander Inspector Warwick Morehu says police encourage staff to speak up if they have concerns.
"This demonstrates that police will take action to question and improve its own processes; even when the individual involved makes no complaint and suffers no injury."
He would make no further comment because the incident is subject of an employment enquiry under the police code of conduct.