Dr Jim Sprott was a scientist willing to face the wrath of the establishment to fight for what he believed was right.
He was best known for his key role in the freeing of Arthur Allan Thomas and for his controversial theory - developed in a survey conducted in Southland - on the cause of sudden infant death syndrome (Sids).
Sprott died aged 89 at Auckland City Hospital after a brief illness.
Journalist Pat Booth said he and Sprott were "joined at the hip" in their work on the Thomas case.
"He had a great mind and a great determination, and we used both of those to the full," he said.
Other issues on which Sprott made a stand were road safety and the painting of the Auckland Harbour Bridge.
He also opposed the Labour government's policy in the mid-1980s to ban nuclear ships entering New Zealand ports.
Sprott received a doctorate in chemistry from Auckland University and ran his firm of consulting chemists between 1952 and 1983.
In 1995, he was awarded an OBE for services to forensic science and the community.
He spent years trying to get justice for Thomas, who was given a royal pardon in 1979 after twice being convicted of the 1970 murders of Waikato farming couple Jeanette and Harvey Crewe.
Sprott's key contribution to the freeing of Thomas came after retired detective Jack Ritchie, who ran a gun shop in Dannevirke, came up with a theory that the bullets used to kill the Crewes were never in the type of cartridge that police alleged they found in the Crewes' garden.
Ritchie sent examples to Thomas retrial committee chairman Pat Vesey, who passed them to Sprott.
As recorded by the royal commission into the Thomas convictions, Sprott advertised in the press and on radio at his own expense, asking the public for as many cartridge cases as possible of the type involved.
He obtained about 26,000 and examined most of them himself.
There were no matches between the type of cartridge case and the bullets used in the killings.
The commission found that the case was planted by police in the Crewes' garden.
It described Sprott as "the man who in our view more than any other was responsible for the eventual release of Mr Thomas".
Sprott sought compensation of $150,000 for the hours he had put into the Thomas case. The commission decided he should get $50,000.
At the height of the Thomas retrials, appeals and royal commission of inquiry, Sprott's neighbours did not want to talk to him, and his teenage children got into arguments when their surname was mentioned.
The second issue that resulted in Sprott being in the public eye for years was his high-profile promotion of the theory that Sids was the result of poisoning by gases produced by microbial activity in cot mattresses.
It was a theory developed after he conducted a 1988 survey of Southland parents whose babies had suffered cot deaths.
In 1989, British chemist Barry Richardson identified the gases and identified a common fungus as probably the principal organism able to generate the gases.
By 1990, following wide publicity in Southland of Sprott's call for a rejection of synthetic chemical-induced sterility, to old- fashioned washing with soap and water, and washing and boiling feeder bottles and teats, the cot death rate in the province had dropped from an average of 8.5 per 1000 live births in the three years to 1988, to 2.8 in 1989.
In 1994, Sprott decided to promote a public awareness programme to prevent cot death - the term he preferred to use - based on the toxic gas explanation and involving mattress-wrapping.
In a 2004 article, Sprott pointed to a reduction in the New Zealand cot death rate from 2.1 per 1000 in 1994 to 0.93 in 2002 as proof of the success of mattress-wrapping.
Sprott said that, during the period covered in the article, no cot death had been reported when a baby had been sleeping on a mattress wrapped according to a protocol.
The toxic gas theory was opposed by many Sids researchers.
A 2012 article in the New Zealand Medical Journal attributed the big decline in Sids deaths to changes in infant sleep positions - from sleeping on the stomach to the side, and then predominantly to sleeping on the back. Fairfax NZ
- The Southland Times