Two police officers who deliberately kneed a man in the head and stood on him during an arrest used "gratuitous" violence which was an abuse of power, a watchdog has found.
The officers have both been disciplined, with one resigning, after they kneed and stood on the offender.
The pursuit took place in South Auckland on October 26, 2016, after a man reported his ute had been stolen in Bombay.
The vehicle was located and pursued through countryside by police and the Eagle helicopter for about 15 minutes.
The fleeing driver rammed the pursuing police car before he eventually surrendered to police on a private farm.
Eagle footage showed the man stopped the ute and got out with his hands in the air.
He then lay face down on the ground with his hands behind his back. Several officers assisted in arresting and handcuffing him.
An Independent Police Conduct Authority report released today details how during the arrest, an officer deliberately kneed the man twice in the head, causing facial injuries.
The report said the officer's use of force "was completely unnecessary, and he had no justification for it under police policy or the law".
"The authority considers that [the officer's] use of force against [the man] was intentional and gratuitous.
"It is especially concerned that the force was used when [the man] was in such a vulnerable position and considers this to be a gross abuse of power."
While the man was lying on the ground handcuffed, a second officer also intentionally stepped on his leg.
The IPCA also saw this act as a "deliberate and gratuitous force used on a vulnerable person - although at the lower end of the scale in terms of seriousness".
However, it took into account that the second officer had reflected on the matter and acknowledged that it was inappropriate.
The arrested man later received treatment for his injuries at Middlemore Hospital and laid a complaint with the IPCA.
He said police "stomped" on his head, causing him to lose consciousness, and he had ongoing headaches as a result of this incident.
The authority found that both officers unlawfully applied force to the man.
Judge Colin Doherty said: "The officers used intentional and gratuitous force against the man when he was in a vulnerable position, restrained on the ground. Their actions were an abuse of power."
Police charged the first officer with wounding with reckless disregard. The officer pleaded guilty and was discharged without conviction by a District Court judge.
He resigned from police following the incident.
The second officer was sanctioned by police following an employment investigation.
The IPCA also identified issues regarding the police investigation into the complaint.
"In summary, the authority found that there were a number of initial errors or
miscommunications in examining and categorising the complaint for investigation," the report said.
"Further delays and errors within the process meant that the initial investigation was substandard."
This findings have been raised with the Commissioner of Police.