For 40 years, Jack Collins kept a secret about an unsolved Rotorua murder, known only to himself and wife Irene.
But before the Taupo man died in 2010, he shared that secret with one other person - local author, journalist and researcher Chris Birt, who has recorded Mr Collins' story in his new book All the Commissioner's Men.
Mr Birt said what Mr Collins told him was shocking. It was that the late Assistant Commissioner of Police Bob Walton, irritated about having five unsolved murders hanging over the New Zealand Police, had ordered Mr Collins, then a detective sergeant in the Rotorua CIB, to further investigate a murder suspect who he believed was innocent.
Mr Collins refused, saying based on the evidence he did not believe the person was responsible for the murder of teenager Olive Walker in Rotorua in May 1970. Mr Collins believed he had a solid lead on another person.
The murder has never been solved.
"Walton knew that a relation of Olive Walker's had a criminal background and was trying to get Jack to target that guy and Jack was saying that construction size six shoes which were common at the Waipa Mill at the time, were all over the scene.
So he knew the murderer had size six shoes, and this guy didn't," Mr Birt said.
According to Mr Collins, Mr Walton told him he was finished in the CIB. The next day he was handed a letter saying he was being transferred back into uniform and shifted to Wellington. He never worked in the CIB again.
Mr Birt believes that when Mr Walton travelled on to Auckland later the same day for a conference with the detectives invesigating the murders of Harvey and Jeanette Crewe, he put the investigation team there under the same pressure, saying they had to drive for evidence and make an arrest.
A decade later, a Royal Commission found police evidence against Arthur Allan Thomas had been deliberately planted, and that he should be pardoned for the murders, for which he had already served nearly 10 years' prison time.
Mr Birt has dedicated his book to Jack Collins, in recognition of his courage in standing up for his oath of office and for the community he served.
Mr Collins' widow Irene said she cried when she first read it, because her husband had never got over what had happened to him. To have his actions out in the open was a relief after 42 years of keeping the secret.
Mrs Collins said although Mr Collins hated having to spend the last 15 years of his career in uniform, he never regretted doing the right thing. From Wellington, they transferred to Hamilton, then Gisborne, then back to Rotorua, eventually retiring near Taupo. He attained the rank of Chief Inspector, but never again worked in the CIB, although that was his passion.
She believed that after simmering about the conversation with Mr Walton for so long, Mr Collins realised when he was dying that he needed to share the story of his encounter with Walton and the repercussions.
Mr Collin's daughter Marilyn Collins-Dawson said her father was very loyal to the police even though she believed that police officers with unsolved murders were sometimes given a hard time.
"You could walk into a room and have people say 'still got that unsolved murder on your plate Jack?' and they were under a lot of pressure to be seen to be doing the right thing by their superiors."