Attending hundreds of serious crime scenes during this time, the senior forensic crime scene examiner was involved in high-profile homicides including the 1970 Crewe murder at Pukekawa.
For Arnold, the Rainbow Warrior investigation wasn't different to any other case. He became involved with it after the initial investigation.
"The Rainbow Warrior, although it is important because of the result - and what the result meant for NZ, it was just another case."
Circumstantial evidence had already been procured by detectives, who had travelled the world trying to secure evidence to directly link main suspects Alain Marfart and Dominique Prieur to the crime.
The vessel, Ouvea, was known to have been used by French Secret Service Agents whom police suspected had been involved in the bombing, which was later sighted by the Australian Police in Norfolk Island.
A team of CIB detectives and a fingerprint expert were sent to the island to secure evidence from the ship, Arnold said.
Once the evidence had been uplifted and brought back to Auckland, Arnold and his team had to quickly find and photograph latent fingerprints on the large volume of salt-encrusted ship papers.
"At the top of their list was to trace the fingerprints of Marfart and Prieur on any of the papers or maps taken off the vessel Ouvea, as this would provide the missing link in police evidence," he said.
Arnold was then guided to "global forensic experts" who were skilled in locating fingerprints using laser technology.
Expert Ken Creer, of the British Home Office, led Arnold through a "complex procedure" of using this computer-based system. Alongside two senior professors at Auckland University, they began a three-month examination of the paper and maps.
"The laser has a spectrum of light that is dangerous to our eyes," he said.
"Every night for about three months we went back at night when the laser was not being used. And two of the university tops used their skills to set it to the wavelength that we wanted. And away we went."
Months later, they positively identified Mafart's fingerprint on a New Zealand map from the ship. Arnold said it was the "vital evidence" police needed to link Mafart and Prieur to the crimes.
"Straight away he identified it as Alain Marfart. We then had to try and photograph it. We did it all on Polaroid because we couldn't wait for anything else," he said.
"I just think we said: 'Wow, this is it'. We had worked hard, but what we realised was that it took a photographer and an expert fingerprint man to solve the case.
"We both put a lot of our time and experience it into. We pulled it off."
Both suspects pleaded guilty to charges of manslaughter and wilful damage in the Supreme Court at Auckland.
Arnold, who retired in 1988, said he was "pretty tired and worn-out" afterwards.
"Stress was my everyday occurrence to be quite honest, it was a world of stress," he said.
"It was time to go."
Arnold said like all police photographers, he saw the "bad side of life" daily.
"Police photographers have a way of handling things. The first thing that the police psychiatrist did when they came in the mid-80s. The first person they saw was me.
"I was a photographer seeing the bad side of life every day."
Resilience, responsibility and good self-management were just some of the essential skills needed to be a successful police photographer, he said.
