A Corrections officer trainer says a prisoner had already been overpowered before guards used "excessive force" against him, including kicks to the head and dislocating an ankle, a court has heard.
Guards Desmond Faafoi, Wiremu Paikea and Viju Devassy were working at Auckland Prison, Paremoremo, on May 20 last year when officers were attacked by inmates.
Faafoi was stabbed several times in the head with a shank (a makeshift knife).
Police charged the three prisoners who instigated the attack, Samuel Hutchins, Trent Wellington and Mitai Angell, who have all pleaded guilty to wounding with intent to cause grievous bodily harm and aggravated assault and will be sentenced later this year.
However, police also investigated the force used by the guards to subdue the prisoners - particularly Angell.
Faafoi was then charged with assault with intent to injure Angell and Paikea charged with causing grievous bodily harm with reckless disregard to the prisoner.
Devassy was also charged with wilfully attempting to pervert the course of justice for allegedly turning a camera away from the incident.
All three deny the charges and their trial has been playing out in the High Court at Auckland this week.
Today, Robert Hoogenraad, a Corrections officer trainer, said he believed the officers has used "excessive force" when restraining Angell.
"I believed the team had control and whilst that prisoner was under control that excessive force was used," he said.
Shane Tuheke, a veteran Corrections officer in the master control room where the CCTV cameras are operated on the day of the incident, also recalled the "distress" he felt as the prisoners launched their assault.
He first noticed a radio alarm sounding for Bravo block, indicating an incident unfolding.
Moments later "30 or 40" radio alarms were going off.
"I had to make a judgment call because of the severity of alarms that were coming through and radio calls that were coming through," Tuheke said.
"I went to the camera first off to assess the situation ... It was a very serious incident in progress," he said, explaining he focused a CCTV ceiling camera on the attack.
While he couldn't explicitly recall the radio chatter he said it "didn't sound good".
"I do know it was enough to distress me," he said.
Tuheke then radioed for the Corrections A team - an emergency response squad.
However, as he was doing so and the A team was running down the prison's corridors, the camera was shifted away from filming the incident.
"I thought it was odd but it has happened," Tuheke said, unsure why the camera had moved, but assumed it may have been the camera's automated programming.
"Usually once I put a camera on the spot it stays there," he said.
The Crown alleges Devassy deliberately swivelled the camera to avoid filming Paikea injuring Angell.
Devassy denies wilfully redirecting the camera and his lawyer, Paul Borich QC, said the Corrections officer wasn't trying to pervert the course of justice but rather "try and preserve it" and "locate other rogue inmates".
Tuheke said: "For me, I would use what camera I can to see whatever is possible to get an understanding of what is happening.
"I do it to assess the situation, to know if I need to call for medical, or if I need to call for more available staff.
"It may be for evidence," he said.
Yesterday, the court was shown the CCTV footage of the violent incident.
The video shows Wellington being wrestled by a Corrections officer near a stairwell, before Hutchins is then tackled by Faafoi.
Faafoi can be seen bleeding heavily from his stab wounds.
Angell is wrestled to the ground before more Corrections officers, including Devassy, come to help restrain the prisoners.
Smeared and splattered blood can be seen on a wall as the guards regain control.
The Crown, led by prosecutor Jo Murdoch, alleges while Angell was on the ground Faafoi retaliates by kicking the inmate in the head three times.
Devassy's body camera filmed Faafoi's kicks, prosecutor David Wiseman told the court.
Voices from an unknown Corrections officer during the recording can be heard saying: "Des[mond], Des, enough, enough, enough, enough" and "camera, camera".
However, Faafoi's defence counsel Todd Simmonds argues his client, who had just been stabbed several times with a shank, had no malicious intent to injure Angell as Corrections officers restrained the prisoner.
"Multiple blows to his head, stab wounds, cuts, abrasions, bleeding and the effect that had on him," Simmonds said.
"His ability to think straight, to appreciate what he was doing at the time - that's the defence.
"He may have lashed out, you'll see that on the footage, but did he have the intent?"
The CCTV footage also shows Paikea kneeling down over the back of Angell's legs.
It is during this period the Crown alleges Paikea deliberately bent Angell's ankle at a 90-degree angle causing a compound dislocation.
Aaron Perkins QC said Paikea accepts the gruesome ankle injury occurred while his client was wrestling with the inmate.
But Paikea rejects any criminal intent or reckless disregard for Angell wellbeing.
"[Paikea] was simply doing his job in very difficult circumstances to the best of his ability," Perkins said.
The trio of officers were suspended after the charges were laid.
Their trial, which is expected to last two to three weeks, continues.