The company owner convicted for a workplace death and now pursued by police for allegedly putting profit before safety has previously been convicted of careless driving causing death.
The tragic detail emerged in court documents that show police are studying years of profits at Salters Cartage Ltd before the 2015 explosion at Wiri, South Auckland, that killed worker Jamey Lee Bowring, 24.
The documents stem from a police "proceeds of crime" case in the High Court, which has targeted millions of dollars of cars, property and other assets belonging to Ron Salter and his wife Natalie, and their waste fuel recovery business.
Police allege "the pursuit of profit drove" the Salters to "commit significant criminal activity" in the form of years of poor health and safety compliance that emerged when Bowring was killed while welding atop a 96,000 litre tank filled with dangerous fumes.
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The case has been described as a novel use of the Criminal Proceeds Recovery Act - a claim police have rejected.
Salter and his company paid about $400,000 in fines and reparations after pleading guilty in 2017 to 12 charges of breaching health and safety and hazardous substances laws. Salter was sentenced to 4½ months' home detention.
The police action - which came after a WorkSafe prosecution - surprised Salter, who told the Herald last year: "I'd done my time, paid the fines. I thought I'd done everything and it was all over."
The case has yet to move to the main argument with the High Court preparing to release a judgment over whether police should underwrite damage to the business if its proceeds of crime case fails.
But substantial evidence has already been filed, among which was Salter's record of criminal and traffic convictions.
It shows Salter was charged with careless driving causing death in July, 1987. In October the following year, he was convicted and sentenced at the Hamilton District Court to six months' periodic detention and banned from driving for 18 months.
The conviction followed charges in 1974 and 1985 that he had "operated a vehicle carelessly" and one in 1983 that he had "operated a vehicle inconsiderately".
He was convicted again in 1991 for inconsiderate driving and in June 2008 for driving dangerously while at twice the breath-alcohol limit. Salter, 67, declined the opportunity to comment.
The case file showed the court was told the Commissioner of Police's case was that "the pursuit of profit drove" the Salters to "commit significant criminal activity" over a number of years and that Salter and Salters Cartage Ltd caused serious harm doing so.
An affidavit from a detective assigned to the case said police had targeted income made by Salters Cartage Limited from sales of recycled oil processed by the company, and from shipping or storing hazardous substances, when doing so breached breach of health and safety laws.
Documents on the case narrow the period of "significant criminal activity" from 2012 to 2016. The detective said a "substantial benefit" had been earned that was beyond the financial penalty that came with the health and safety prosecution.
The amount of money police were seeking to seize was not disclosed in the documents with the court placing black stripes across columns of figures.
The affidavit detailed breaches of health and safety law which included failing to properly label the gas tank on which Bowring was welding when killed.
It stated the storage tank was labelled in a "materially misleading" way by claiming to contain diesel when it actually held a mixture of "volatile substances with lower flashpoints".
One sample tested was shown to have a "flashpoint" of 17.5C, classifying it as "high hazard". Diesel, by contrast, was rated "low hazard" and ignited between 60C and 93C.
The different substances should have meant "hot work" was prohibited without the tank being specially cleaned and prepared for the task, the affidavit stated. It also said Salter had been told in 2011 the storage tank required documentation.
The affidavit alleged a range of non-compliant equipment and storage across the worksite "meant that there was a significant risk of explosion or fire which was reasonably likely to cause serious harm to any person at the site or in the near vicinity of the site".
The court file included details collected by police in 2015 when it was carrying out inquiries into the fatality, including a statement from its former general manager who told detectives: "I could see at times that [Salter] was under pressure to keep up his family lifestyle".
The former general manager said "the peak of Salters Cartage" was a private sector environmental award won by the company in 2008. "As time went on after that award, there was pressures to maintain the financial prosperity, but the other practices began to taper away - and that included health and safety practices.
"Natalie and Ron would go on holidays very frequently. They would come back for a short time then they would travel again."
In an affidavit for the court case, Salter said the fatality "was a real wake-up call to me about compliance. [Salter's Cartage Ltd] is a very different business now in terms of compliance".
Bowring was working at the business with his mother's partner, who was an old friend of Salter's and not present when the explosion happened. Salter has repeatedly maintained that he said no welding was to be done on the storage tank.
Bowring's mother, Sarah Ferguson, declined to comment. She told the Herald last year she was not surprised at the police case "due to how illegally [Salter] was running his operation".