The Corrections Department is carrying out a review of double-bunking prisoners after two separate cases of repeat sex offenders raping their cellmates.
In both cases, Corrections staff allowed the repeat sex offenders to double-bunk with younger men. One of the rapists, William Katipa, was this morning sentenced to preventive detention - for a second time.
According to the terms of reference for the review, released to RNZ under the Official Information Act, acting chief executive Jeremy Lightfoot asked senior Corrections staff to carry out a review of the risk assessment process.
The terms of reference said there had been "recent incidents" and it had been found that staff did not follow the correct process.
"There have been recent incidents where, upon examination, it is evident that the [risk assessment] process either has not been followed as per policy, or, despite being followed, prisoners' safety has still been compromised."
It called for a full review and said if shortcomings were found recommendations should be made immediately.
The review was called for in August - in the middle of William Katipa's trial.
Katipa was already serving a preventive detention sentence for two rapes. He was jailed for raping a 13-year-old, and raping a young mother in front of her two year-old daughter.
The Crown's case is that Katipa told other prisoners of his gang connections and that he was in for life, meaning he had nothing to lose.
Despite Katipa's convictions, he was able to have cellmates.
He used threats of violence and knocked one of his cellmates out before raping him during lock-down. He raped one of his victims for a week.
One of Katipa's victims is suing Corrections for hundreds of thousands of dollars, while a second has asked for $75,000.
Katipa was sentenced at the High Court in Auckland today for offences including sexual violation and threatening to kill.
Justice Downs said Katipa's prospect of getting treatment was highly unlikely given he had told a psychiatrist he would maintain his innocence to the end.
The judge summed him up up as being unremorseful and dangerous.
Katipa will have to serve a minimum of 15 years and then prove he is no longer a threat to the community before he has any prospect of being released.
The morning's sentencing is largely academic - given his current sentence has no specific end date and a prisoner can't serve preventive detention sentences back-to-back.
But it will send a message to the Parole Board should Katipa ever appear before one.
Katipa's case followed that of Stephen Mark Gotty, a repeat sex offender with more than 140 previous convictions.
Gotty sexually abused his young cellmate. He was sentenced to preventive detention earlier this year.