His death in the former Soviet outpost on the Caspian Sea leaves many unanswered questions amid allegations of fraud and a string of angry creditors, including former friends and employees of his funds management business.
Mr Allen founded APT Capital Management in Melbourne in 2009, with the company first registered to a nondescript townhouse in Murrumbeena.
By 2014, Mr Allen had leased premises at 101 Collins Street and established offices in Hong Kong and Singapore.
Mr Allen told clients his firm offered the best investment opportunities across the Asia Pacific region, but he also spent significant periods of time in the Cayman Islands and the Russian city of St Petersburg.
A former employee said he always travelled in business class and lived an extravagant lifestyle.
Mr Allen relocated to Hong Kong with his wife and young child in about 2016, according to corporate records. About the same time, the Australian Tax Office began to audit his business affairs.
In 2018, Singapore authorities froze the trading accounts of APT Capital Management as part of an anti-money-laundering investigation, according to several former staff who claim they were never paid by Mr Allen, or had to threaten legal action.
As his business collapsed, Mr Allen abruptly moved his family to Azerbaijan in 2019.
The outcome of the money-laundering investigation has never been revealed, with the Monetary Authority of Singapore declining to respond to questions from The Age.
“Neither APT Capital Management nor Mr Simon David Allen are regulated by MAS. We do not have further information on Mr Allen or his company,” a spokeswoman for the Monetary Authority of Singapore said.
A spokesman for the Hong Kong Monetary Authority also declined to comment, other than to say Mr Allen’s investment company also fell outside its regulatory jurisdiction.
However, a liquidator’s report into the collapse of another company owned by Mr Allen raises serious fraud allegations and also reveals he owed $16,001,520 to the Australian Tax Office.
The report by Pitcher Partners refers to documentation from the Deputy Commissioner of Taxation that accuses Mr Allen of using a gift importation business called Multivate Pty Ltd to facilitate a “sham operation” with its ultimate holding company APT Capital Management.
“The Deputy Commissioner of Taxation alleges the company knowingly lodged fraudulent business activity statements, whereby the company would claim input tax credits on expenses it had purportedly incurred,” the liquidator report from August 19 states.
An audit of the company between 2014 and 2017 also reveals that $5,848,525 was transferred to APT Capital Management, while his wife was paid an annual salary of $531,836 in 2017.
A search of Mr Allen’s assets in Australia uncovered a Westpac account that was overdrawn by $22, while a former secretary in Melbourne was still owed $12,000 in unpaid wages.
The liquidator report identified eight potential breaches of the Corporations Act, which were reported to the Australian Securities and Investments Commission in August 2019.
An ASIC spokeswoman declined to comment when contacted by The Age.
The ATO also declined to respond to questions about Mr Allen, citing its “obligations of confidentiality under the law”.
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Senior Crime Reporter