In an intriguing twist on the final day of the siege inquest's current sitting, Monis' former accountant and personal assistant revealed that in the mid to late 1990s the gunman had lived in an exclusive gated community and was married to the daughter of the Dean of the University of Tehran.

"He could have had the best life … very rich, very powerful," said the 47-year-old whose name was suppressed to protect his Iranian relatives.

"I think he just done [the siege] for himself. He always just thinking he better than the others … he know better and he have to do something – always big."

The former accountant said Monis had an elegant lifestyle, including a house stocked with expensive furniture and a series of rented apartments, which appeared to have been paid for by a scam involving products purchased from the Iranian government.

He said he had helped Monis register a company called Salhani Amal – which means the people who are well behaved and do good deeds – through which he would purchase large numbers of tyres from the Iranian government at discounted prices.

Monis would then sell the tyres on the black market for a substantial profit

"In that time it was a big money ... each trade was [equivalent to] twenty-five to thirty thousand dollars Australian," the man told the inquest.

"It was … illegal, but at that time in Iran everyone was doing it."

The man said that after a while Monis moved out of the tyre business and began offering his services as a fixer.

"To start with it was just buy and sell … then he got involved in helping people … people with a problem with the government," the man said.

"He used his power, mainly friends, connections … helping the business man who got a problem."

The former accountant said he did not know whether Monis paid kickbacks to the Iranian government, but recalled being asked by his boss to deliver bank cheques for tens of thousands of dollars to government officials and other prominent officials.

Monis had set up a faux charity to give the impression of propriety and to avoid paying tax, buying fridges and televisions for organisations which housed the poor.

He also revealed that just before Monis fled to Australia he ripped off his partner in a travel agency business.

This had occurred shortly after the failure of the businessman's self-published poetry book, entitled Depth Internally and Externally – a defeat which Monis apparently felt keenly.

"When the book come out he think he will become famous person … but nothing happen," the former assistant said.

"He even printed second edition … but no-one want the book, no one like the book."

The book was also notable for its liberal ideology – a far cry from the religious fundamentalism which Monis later espoused.

The former assistant said he had been shocked to discover this "turn to extremism" after he joined Monis in Australia in the mid-2000s, suggesting it was another attempt by Monis to achieve notoriety.

"When he came here he tried to become famous again … he chain himself to the Parliament … he write the fatwah."

"He never [really] support the religion … he very liberal … but no one was thinking he was an important person … he was disappointed."

The inquest will recommence in November to examine Monis' engagement with Australia's national security agencies.

Much of this section will be closed to the public and the media.