A newly released internal police report claims a senior detective in charge of child protection investigations did not initially report improper contact between a teacher at the school he helped govern and a student who later took her life.
Theo Ackroyd was a detective sergeant at Gisborne police at the time - and also the chairman of the board of trustees of the school where teacher Sam Back had taught Reiha McLelland.
He accepted he had a conflict of interest when police began investigating Back's intense relationship with Reiha, 13, before she took her life in August 2014.
But it has emerged his actions around the case led to an employment investigation and an inquiry into whether there was criminal culpability.
The internal report, released through the Official Information Act, was sparked by media reporting of Ackroyd's conflict of interest after he sought name suppression for Back and Gisborne Intermediate when the Teachers' Council heard a complaint against the teacher.
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It shows police national child protection coordinator Detective Sergeant Natasha Allan probed the timing of the police's notification to the Education Council of improper contact between Back and Reiha.
The schoolgirl stayed nights at the house Back shared with his partner Angie Mepham, also a teacher. Reiha and Back also exchanged around 4000 text messages in the three months before the relationship was discovered in April 2014.
Allan found police closed the inquiry on July 30 after the trainee detective assigned to the case met Reiha's parents to say no evidence of criminal offending had been found. Back has always denied there was a physical aspect to the relationship with Reiha.
Ackroyd, despite having told the trainee detective he had a conflict of interest, noted in the police file he had reviewed the investigation and sent it for filing because there was no prospect of conviction.
He wrote: "Known lines of enquiry have been completed. No evidential statement of complaint forthcoming. Given the overall circumstances no further investigative action required."
At that stage, Ackroyd had already sat on the intermediate school's disciplinary committee, which had cautioned Back, given him a final warning over inappropriate contact with students yet allowed him to remain teaching.
Reiha committed suicide on August 1. That day, the file was again reviewed by the officer in charge of the Eastern District police child protection team, Detective Senior Sergeant Dave Greig who said "extent and nature of the contact between McLelland and Back has been completely inappropriate".
"This must be addressed and in these circumstances I believe that we have at least a moral obligation to fully inform the school and the Teachers Council of such."
Greig said the file should be returned to the trainee detective to liaise with police legal services so letters could be drafted to the school and the Teachers' Council.
Three days later - August 4 - Greig recorded in the police computer system: "Advised by D/S Ackroyd that the BOT and the Teachers Council have already been advised."
Allan's internal inquiry showed she contacted the Teachers' Council - now the Education Council - to find out when it had been notified about the case.
The internal report showed the Teachers' Council learned of the case on August 6 when contacted by a member of the NZ School Trustees' Association "who was concerned that no mandatory report had been made by the board".
The internal report stated: "This call from NZSTA was received two days after D/S Ackroyd advised D/S/S Greig a notification had been made to the Teachers' Council."
Allan said the Teachers' Council contacted Greig on August 7 who was with Ackroyd at the time of the call.
"The mandatory report from the school was received by the council later that day," the internal review stated. It had been sent by Ackroyd, as board of trustees chairman, from his police email address.
The internal review said: "The [Teachers'] Council were very concerned that the (Board of Trustees) had not notified them of this investigation as soon as possible. Back had remained teaching up until they were advised."
After the notification to the Teachers' Council, Back signed a voluntary agreement to cease teaching and stopped on August 15, 2014.
The internal review also said there was "no evidence" Ackroyd had notified Greig about the conflict of interest. Ackroyd later told the inquest he had done so by telephone.
Ackroyd's conflict of interest was first identified by the Herald after it emerged he had sought name suppression for Back and Gisborne Intermediate in his role as board chairman through a letter sent from his police email address.
In the letter, which also gave his police email address as a point of contact, Ackroyd said suppression was necessary to avoid damage to the school community and to Back's reputation, as the school intended he would return as a teacher.
Ackroyd also said suppression was necessary as "identification of Mr Back or Gisborne Intermediate may prejudice any future charges that may be laid against Mr Back or any other party in relation to the death of the student".
At that stage, there was no police investigation into Back's relationship with Reiha, or into Reiha's death.
Detective Superintendent Chris Page said police would not comment on employment matters.
Asked if there was a criminal investigation into Ackroyd's role, he said: "The investigation included an assessment whether there was any criminal liability by persons involved in the case. There was no evidence to support a criminal case."
Page said the request that the Teachers' Council be told of Back's relationship with Reiha had been made to Ackroyd and the trainee detective who investigated and this had been done.
During the inquest, Coroner Carla na Nagara said Ackroyd's conflict of interest would not be a focus of inquiries as it was more properly dealt with by the Independent Police Conduct Authority.
The IPCA published a report late last year in which it found Ackroyd's conflict of interest was not properly managed, that he had involvement in the investigation he should not have and that the investigation was incomplete.
During the inquest, Downes said Ackroyd's role had no bearing on the investigation and he would have charged Back if there was sufficient evidence. He said suggestions he had been influenced in such a way were "pretty tough to read".
The inquest was not provided with the police internal inquiry and the IPCA report did not set out the timeline, which contradicted Acroyd's claims he had informed the Education Council.
The McLelland family did not wish to comment but their lawyer, Moira Macnab, said the internal review should have been provided to the inquest. It was completed the month before it began and would have provided information helpful to understanding the actions police had taken.
Back has been struck off as a teacher and his partner Mepham cautioned.