Long-time Arthur Allan Thomas campaigner Pat Booth has decried a new book on the controversial 1970 killing of Pukekawa farming couple Harvey and Jeanette Crewe.
Mr Thomas was twice convicted of murdering the couple, before being pardoned in 1979 and given nearly $1 million in compensation from the Government.
However, in The Final Chapter, released yesterday, author Chris Birt claims the killer was Jeanette Crewe's father, Len Demler, an early suspect in the police investigation.
Birt says in the book that Mr Demler killed his daughter and son-in-law because of a craving for wealth and status, but took his secret to the grave when he died in 1992.
Mr Demler was also motivated by financial problems as he had had to sell half the family farm to pay a £10,000 fine for tax evasion in 1961.
Family feuding followed and when his wife died, half the farm and $12,000 of shares he had paid for were in her estate and controlled by Jeanette Crewe.
With Jeanette dead, Mr Demler had control over his wife's estate, Mr Birt argues.
The Crewes' killer has never been brought to justice.
Birt's book centres on Mr Demler's behaviour after the murder, and his motives for the killings. Birt spent 25 years researching the book.
The author also claims that he knows the name of the mystery woman who is believed to have fed the Crewes' baby, Rochelle, who was left alone in the house for five days after the murders.
Earlier books have speculated on the woman's identity.
Birt said he knew who the woman was but did not know if she was alive. He said he had not named her in his book for fear of attracting a defamation action.
He claims Mr Demler was seen dumping the bodies in the river by a casual farm worker, who saw a man fitting his description carrying two bundles.
But former Auckland Star editor Pat Booth, who campaigned to have Mr Thomas freed, said Mr Demler's involvement had been thoroughly investigated by police and there was no strong evidence to suggest he was the killer.
But Mr Booth believes Mr Demler was involved in disposing of the two bodies, after Jeanette Crewe shot and killed her husband during a heated and violent domestic row, then killed herself several days later.
He said that by October, four months after the killings, police believed they had enough evidence to arrest Mr Demler for the killings, but were convinced the evidence was not strong enough to get a conviction by the Assistant Police Commissioner, Bob Walton.
Three weeks later, Mr Thomas was arrested and charged with both murders.
Booth said yesterday that Mr Demler and Jeanette Crewe had both probably disposed of Harvey's body.
He said Mr Demler then "discovered" and reported the bloodstained house on the Monday.
"It is obvious Harvey Crewe was shot on Wednesday night after a domestic in the house after he has assaulted Jeanette and caused her quite an injury," Mr Booth said.
"My belief is that she and her father disposed of Harvey's body, tried to clean up the house and couldn't."
Jeanette was under severe physical and psychological pressure and probably called Mr Demler to tell him she was about to kill herself on the Saturday or Sunday.
"He then came and disposed of her body and later went through the pretence of discovering the house," Mr Booth said.
There was no evidence to suggest Mr Demler was the killer, although Mr Booth believed he was involved in the disposal of both bodies, to protect the reputation of his daughter and grand-daughter.
Mr Demler had nothing to gain from the death of his daughter and son-in-law because the farm went to the couple's daughter, Rochelle, he said.
Had he murdered them both to get the farm, he would have had no qualms about killing Rochelle to ensure the farm passed to him. "He would have foreseen the fact that the wills of the two parents would have left the property in its entirety to Rochelle, which it did."