The sergeant accused of kicking a prisoner in the groin and assaulting four others has told the court that eight of his police colleagues have got it wrong.

Martin James Folan has sat in the Auckland District Court through eight days of evidence which has included CCTV footage from the Henderson police station, where he worked as a custody sergeant.

He has denied six counts of assault.

The assaults are alleged to have occurred in the four months after Folan was transferred to his new job. He told the court that he never wanted the West Auckland-based role because he lived on the North Shore.

Folan denied elbowing 16-year-old Finn Campbell in the face as the teenager sat handcuffed in the back of his patrol car.

He also denied kicking a drunk Samuel Verdonk who was loud and banging his head against his cell door.

Folan said Verdonk "came flying at me" so Folan used the ball of his foot to push the prisoner off balance.

Folan is also accused of banging the head of prisoner Jerrilee Tuiva against the concrete floor of the police station twice, for which he faces two charges.

"Incorrect. It didn't happen."

The court has also heard that Folan is alleged to have lost his temper with a fourth prisoner, Minora Kea, and throttled him in the processing area.

"My right hand was on his jawline. There wasn't a lot of pressure."

He said he had approached Mr Kea because the prisoner was making threats and "amping himself up".

"I told him, 'I told you - pull your head in, you're getting bailed."'

Asked if he had squeezed Mr Kea's neck as Crown witnesses have said, Folan said: "No, that's incorrect."

Folan is also alleged to have kneed prisoner Joseph McGee in the groin as Mr McGee struggled in the processing area. Two constables who were helping Folan to secure Mr McGee have said they saw Folan's knee come up and connect with the prisoner.

"I deny it, it's incorrect," Folan said.

Crown prosecutor Mark Zarifeh took Folan through all five alleged assaults during his cross-examination.

"I suggest that you, in your hands-on approach in dealing with people, that you did get riled by the attitudes of resistance in these incidents, that you lost it, you lost your temper and you used force in doing so.

"And that's what is at the essence of what occurred in the space of four months," Mr Zarifeh said.

Folan replied: "I do not accept that."

He also denied recalling conversations with a fellow sergeant where he is alleged to have admitted to two of the incidents.

Mr Zarifeh said Folan's denials and his reasons for using force directly contradicted at least nine police witnesses who have given evidence in the trial so far.

"What you say is: Finn Campbell is wrong in his account of what happened. His father got things wrong. Constable [Reuben] Jakich got it altogether wrong, according to you.

"Constable [Scott] Sherer got it wrong about what happened at the cell door with Verdonk," Mr Zarifeh said.

"So all nine people have got it wrong but your recollection is correct?" he asked.

Folan said he had been telling the truth "to the best of my recollection".

"I answer that by saying that they were all working together or nearby and they have quoted in their statements that there were Chinese whispers going on."

Mr Zarifeh and Folan's lawyer, Richard Earwaker, will sum up their case today.