A man facing jail after being caught in one of Australia's biggest tax stings is also set to be a star witness in the prosecution of two Thai men accused of murdering a good samaritan in Melbourne.
Gregory Dunn, 54, was convicted late last year of conspiracy to defraud the Commonwealth, linked to the $430 million Wickenby tax avoidance investigations dating back to offences committed more than ten years ago.
Dunn, described by some as a tax genius, was convicted of masterminding schemes linked to some of Western Australia's major mining entrepreneurs; which also allowed him to avoid paying more than $2.5 million in tax.
At a sentencing hearing in Perth, it emerged that while being held in custody in Thailand following his 2012 arrest, Dunn had been told vital information about the murder of Melbourne man Luke Mitchell.
Mr Mitchell, a chef, died in 2009 after being bashed and stabbed while attempting to help a man being assaulted outside a nightclub.
Defence lawyer Lisa Boston told WA's Supreme Court that Dunn had instigated contact with the Australian Crime Commission about what he had been told, which was passed on to Victoria police.
"Mr Dunn is the reason the Victoria police have the relevant information - he personally got the ball rolling," Ms Boston said.
Two men - Sarud Seehaverachart, 31, and co-accused Thatiya Terdputham, 38 - have both since been extradited to Australia, and appeared in court charged with Mr Mitchell's murder.
Ms Boston asked Justice Eric Heenan to take into account Dunn's help in the unsolved case when sentencing him for his own crimes.
She also urged the judge to consider Dunn's "grim ordeal" during 43 days on remand in a Thai prison before returning from his adopted home in January last year.
Dunn was convicted for his part in a scheme he designed with accountant Trevor Thomson to help mining services group Barminco protect a $32 million-plus tax avoidance scheme.
Thomson, who had already been convicted and jailed for his part, was blamed for much of the scheme by Dunn during the trial and in sentencing submissions by Ms Boston.
She also claimed Dunn had little financial motive to mastermind the tax avoidance scheme, other than to maintain his business relationship with Barminco bosses Ron Sayers and Peter Bartlett.
But prosecutor Alan Troy pointed out the relationship had earned Dunn more than $11 million and evidence pointed to him as the architect of the conspiracy.
"The Australian Tax Office relies on honesty and he has corrupted that system - and he has shown no remorse," Mr Troy said.
The jury in last year's 11-week trial failed to reach verdicts on Mr Sayers, currently the managing director of Ausdrill, and his friend and Barminco director and co-founder, Mr Bartlett. Accountant Deborah Grace was acquitted of her charge in relation to the conspiracy charge.
Dunn will be sentenced in February.