Each commissioner had a "Judge's Notebook" in which they recorded notes about evidence and their personal impressions. Justice Taylor and Archbishop Johnston's diaries are held in the Archives NZ under sealed order until 2040.
Mr Gordon's family kept his papers after he died in 1994 before passing them to the Hocken Collections at the University of Otago.
The Herald visited and read the diary and the full transcript of the royal commission hearings carrying Mr Gordon's marked areas of interest.
The diary focused on the planting of the cartridge case used to convict Mr Thomas and the role of murder inquiry head Bruce Hutton, who was found to have planted it.
Mr Gordon's notes mainly contained observations rather than statements on findings. Testimony was carefully recorded along with his impressions of those who gave it.
He had a separate sheet inserted into the diary dealing with the accusation the cartridge case was planted. On it, he detailed pivotal points of evidence around the cartridge case, which was found in a garden outside the Crewes' home which had twice been sieve-searched by police. It was later proved to have no connection to the lead bullets found in the heads of the murdered couple.
Throughout the diary, he returned repeatedly to Hutton. He wrote: "Hutton difficulty in recalling Thomas R(ight) or L(eft) handed." Another note said: "Hutton wrong on research of fine ashes." It stated Mr Hutton "ducks questions of Judge on Yes/No answer. Finally extracted". In other places he noted Mr Hutton was "in trouble" or "reluctant" and in one place "evasive". Mr Gordon recorded from Hutton: "Don't believe it was planted." Then, after a question about the storage of ammunition, he noted: "Does not advance acceptable reason."
The notes also recorded Mr Gordon's belief of instances in which Mr Hutton's evidence departed from testimony by others. In places, Mr Hutton - who had left the police force by the 1980 hearings - was left giving testimony which was contradicted by serving officers he had once commanded.
Mr Gordon's son Greg said his father was profoundly affected by reaching the belief the cartridge case was planted. "He was so upset by what he heard. That really rocked him to the core."
He said he saw his father angry twice. The first time was when Sir Robert stole a march on a project he had worked on for political reasons. The second time was during the commission after testimony over the suspect cartridge case - and the anger then turned to tears.
"It broke him when he found out they had planted the evidence in the garden. He was mortified."
The Herald contacted Mr Hutton as one of the few at the commission hearings who is still alive. "Not many of us left now," he said. "I'm 84." He said he had no interest in reading the diary.
Lawyer Peter Williams QC, who represented Thomas at the commission, said it was "shocking" the other diaries and other material from the hearing remained secret more than 30 years on.
"Justice has got to be seen to be as transparent as possible. All these things should be readily available."
He said the case was to New Zealand what Watergate was to the United States, leaving our nation healthier and stronger as a result.
Mr Williams said his review of the diary - copied by the Herald - revealed the commission's growing frustration with police as the hearing progressed. He said the police packed the commission gallery, the police lawyers walked out in protest and officers showed arrogance from the stand.
Police are reviewing the Crewe murder file after a request from the couple's daughter Rochelle. The review includes considering fresh calls by Arthur Thomas' brother for action against police involved in the inquiry.
Mystery for 43 years
The murder of Harvey and Jeannette Crewe is one of New Zealand's most enduring mysteries.
The bodies of the married couple from Pukekawa, who were killed in June 1970, were found in the Waikato River months later. The nation was haunted by the eerie country killings which left baby Rochelle, 18 months old, abandoned in her cot for days.
Police arrested Arthur Allan Thomas, a nearby farmer, and charged him with their murder.
He was convicted, jailed and then freed, then convicted and jailed again before being pardoned and freed after a compelling campaign by journalist Pat Booth and scientist Jim Sprott. A subsequent Royal Commission of Inquiry into the conviction found Mr Thomas had been convicted on evidence planted by police officers.
Mr Booth speculated the case was a murder-suicide, with Mrs Crewe the killer and her father, Len Demler, dumping the bodies. Author Chris Birt has named Mr Demler (now dead) as the killer. Mr Thomas' brother Des believes another man to be responsible.
After 40 years' silence, Rochelle Crewe asked for the investigation to be reopened. She also asked why officers found to have planted evidence were never prosecuted.
Detective Superintendent Andy Lovelock was appointed in 2011 to investigate the original homicide case. His inquiry has widened to include complaints by Des Thomas against the surviving officer accused of planting evidence.
