Documents released through the Official Information Act show Mr Hutton was interviewed by the officers leading the review in January 2012. He died 15 months later in April 2013. The Thomas family have asked why he was allowed to die without being prosecuted. The interview was the first formal occasion on which Mr Hutton was questioned about the planting allegation since the 1980 royal commission hearings.
Read more: Crewe murders: Profile of the killer
Detective Superintendent Andy Lovelock confirmed the interview, saying the meeting "included discussion of exhibit 350".
"Mr Hutton believed there was no issue regarding the integrity of the exhibit or the way it was found."
Mr Lovelock confirmed receiving "complaints from [Arthur Thomas' brother Des] Thomas in October 2012".
He said the issues raised by Mr Thomas about the cartridge case had been "addressed in detail" in the report. The section he nominated repeated the finding of the Solicitor-General of the time that it would not have been possible to prosecute Mr Hutton - a finding Mr Jones' oversight report contradicted this year.
The section also included dismissal of other complaints by Des Thomas, which he had addressed to the commissioner and asked be treated as formal criminal complaints. Mr Thomas told the Herald that Mr Jones' report into the investigation showed Mr Hutton should have been charged.
Crewe review: The full report
Peter Williams, QC, who represented Arthur Thomas after the convictions until he was pardoned, said the cartridge case was a "fundamental weapon of the prosecution". He said Mr Hutton's position over the discredited piece of evidence was not surprising. "It's not unusual for criminals to be in a state of denial. Some stay that way all their lives.
"It should have at least gone to the courts. He could well have been acquitted ... You would have thought the charge would be brought."
Commissioner Mike Bush would not be interviewed about exhibit 350. He had earlier removed himself from the review process after delivering a eulogy at Mr Hutton's funeral in which he described it as a "tragedy and irony that a man of such character" should be accused of dishonesty.
In a statement, Mr Bush said the police review included criticism of their position on the planted cartridge case. "Police accept that failure to reinvestigate this case earlier resulted in adverse public speculation over the years."
He said public faith remained strong, surveys showing growing numbers of Kiwis have high or very high confidence and trust in police.
Why was the cartridge case important?
The cartridge case was the key link between Arthur Allan Thomas and the murders. After he was twice convicted, it was shown the bullets found in the bodies of Harvey and Jeannette Crewe could not have come from the cartridge found at the scene of the murders. The cartridge case was made after the bullets were made - making it impossible for it to have carried the bullets which killed the Crewes.
Why was Bruce Hutton accused of planting it?
It is said the Thomas rifle was in his possession during a key period immediately before the cartridge case was found in a place searched on three earlier occasions. In that period, witnesses placed Hutton and another officer at the Crewe house at a time shots were fired.
Did Mr Hutton do it?
The Royal Commission of Inquiry into the convictions said he did. Mr Hutton always denied it, and police have always relied on a Solicitor-General's opinion from 1981 that there was not enough evidence to prosecute. Despite the accusations being made for 40 years, police never did its own investigation into Mr Hutton.
Why does it matter?
Critics of the police have said the refusal by police to acknowledge - or even investigate - such an obvious example of malpractice created a public doubt around controversial cases. They say it created room in the public mind for doubt around high-profile cases such as David Tamihere and the murder of the Swedish tourists, the Bain murders, and Scott Watson's conviction.
Read the first story in this series here.
