The corporate watchdog has abandoned an international investigation of Jack Flader, the mastermind of Australia's biggest superannuation fraud.
Abandonment of the probe ends any possibility of charges being laid against Mr Flader, who a court found was the "ultimate controller" of Trio Capital, which bilked investors of $176 million.
Despite the assistance of Hong Kong and other overseas authorities, Australian Securities and Investments Commission investigators were left frustrated after they were unable to establish a breach of Australian law.
The decision comes as ASIC faces a Senate inquiry into its performance after criticism of its response to misconduct by financial planners at the Commonwealth Bank.
It is believed that ASIC interviewed Mr Flader several times, assisted by the Securities & Futures Commission of Hong Kong, where he is based. Information was also gleaned from tax haven jurisdictions in which Mr Flader operated.
ASIC is believed to have investigated whether Mr Flader committed a wide range of offences, but was unable to mount a prosecution because it could not find enough evidence that he had specific knowledge of events in Australia.
A parliamentary inquiry into the collapse of Trio Capital in May last year slammed regulators including ASIC for their scanty efforts to prosecute Mr Flader.
The following month, ASIC said it lacked evidence to show Mr Flader had breached Australian law, but would provide information to Federal Police, the Crime Commission and overseas regulators.
Since then, "ASIC, the Australian Federal Police and our overseas regulatory counterparts have sought to obtain extra evidence to establish that Mr Flader breached Australian law", ASIC said on Tuesday.
"However, despite this work, there is insufficient evidence to prove Mr Flader breached Australian law.
"In the circumstances, ASIC is now finalising its investigation into Mr Flader."
Trio went into administration in December 2009 and its Astarra investment funds were wound up by order of the NSW Supreme Court in March the following year.
Executive Shawn Richard was sentenced to a maximum 2 years' jail in August 2011 after pleading guilty to dishonesty charges. In sentencing, NSW Supreme Court judge Peter Garling said Richard "acted under the ultimate control and instruction of Mr Jack Flader", who was "the architect and ultimate controller of the scheme".
BusinessDay was unable to reach Mr Flader in Hong Kong on his mobile phone or at the offices of Zetland Fiduciary Group, where he formerly worked.
■Former investment manager Tony Maher, formerly known as Paul Gresham, has been released on bail after pleading guilty to 20 Trio-related charges in Sydney's Downing Centre Local Court on Tuesday.
Maher, 60, of Katoomba, admitted to making false or misleading statements that saw his company, PST Management, reap more than $500,000 in management fees.
He admitted repeatedly overstating the value of the shares of a Trio fund, ARP Growth, held in British Virgin Islands company Professional Pensions ARP.
The matter is set down for sentencing in the Sydney District Court on November 8.