The mothers of two young women murdered by the same man 24 years apart have asked Prime Minister Jacinda Ardern to order another review of the man's case.
Paul Russell Wilson, a groomsman at David Bain's wedding, was jailed in March for the rape and murder of Christchurch woman Nicole Tuxford in April last year.
He had been released from jail in 2010 after serving 15 years in prison for the rape and murder of his former girlfriend Kimberly Jean Schroder in Hokitika in 1994.
Crown prosecutor Pip Currie said in the latest trial that there were "chilling similarities" between the two cases, with Wilson lying in wait, restraining and gagging his victims, before sexually assaulting them and then cutting their throats.
A review commissioned by the Parole Board found in March that the board's decision to release Wilson in 2010 was reasonable.
But Nicole Tuxford's mother Cherie Gillatt and Kimberly Schroder's mother Nancy Schroder have joined together to ask Ardern to order an independent review of the case.
"Nicole was murdered in the most chillingly deliberate, cruel and sadistic way. It should never have happened," Gillatt has written in an open letter to Ardern.
"If it was not for repeated failures by the justice system, my Nicole would be
"I ask you to please help me get an independent review of the handling of the entire case surrounding my daughter's murder carried out."
She said the two mothers wanted justice for their daughters.
"No mother should go through this. We want to try and make sure no other mother and their daughter have to suffer like this again.," she wrote.
"Sadly, Nancy's husband Gary took his own life after hearing his daughter's killer had re-offended and killed mine, meaning this has actually cost three lives.
"We believe Wilson (also known as Paul Pounamu Tainui) should not have been released by the Parole Board after Kimberley's murder, as the Schroders had repeatedly warned them he would murder again but were ignored.
"There were also many mistakes while Wilson was out on parole. I want to make you aware of six separate incidents, which if handled properly by the Police and Corrections, should have resulted in Wilson being recalled to prison.
"It has been so hard for me, trying to get information out of all the different departments (Parole Board, Police, and Corrections). They are all holding things back and blaming each other.
"I do not have the money to get lawyers to help and I am not experienced in doing this sort of thing (my job is helping to care for disabled adults).
"I can see so many failings and it is obvious they all need to be looked at as one, by someone from outside the departments.
"I honestly think it would find things that could stop someone from getting murdered like this again."
Gillatt made a personal appeal to Ardern, who became a mother herself last year.
"If there is anything you can do to help me to instigate an independent review of the handling of the entire case by all agencies involved, I would be so very grateful," she wrote to Ardern.
"I do not want to ever hear of another girl losing her life in such a horrific way and so needlessly, or for another family to have to try and live with the knowledge it should never have happened to them."