Four years ago, Nick Di Girolamo appeared to have it all.

Ten days after his 40th birthday the former managing partner of prominent Sydney law firm Colin Biggers & Paisley, splashed out $4.5 million on a prime waterfront home overlooking Gunamatta Bay at Henley.

He was on first-name terms with all the movers and shakers in the Liberal Party, including Opposition leader Barry O'Farrell and the party's president Arthur Sinodinos, whom he had convinced to join the board of his company, Australian Water Holdings.

Three years earlier, in early 2007, Mr Di Girolamo had abandoned the law to run AWH, an infrastructure company, full-time.

Fast forward to the present day and Mr Di Girolamo is at the centre of an ugly corruption inquiry where he is alleged to have paid himself an exorbitant salary of $1.1 million a year and fraudulently submitted bills to Sydney Water which had nothing to do with his AWH's provision of water and sewerage infrastructure in Sydney's north-west.

Apart from limousines, wining and dining, there were also hefty donations to the Liberal Party.

Mr Di Girolamo also billed Sydney ratepayers for a $2200 gala ball at the Italian Chamber of Commerce, where he was the president.

Also receiving a $15,000 donation was Balmain Tigers, where Mr Di Girolamo was on the board.

How far Mr Di Girolamo had fallen was summed up by a question pitched to him on Wednesday by the barrister representing AWH's disgruntled investors – mainly old family and school friends of Mr Di Girolamo.

"Might I suggest to you in Australian terms you've ripped off . . . Sydney Water, that is the taxpayers of NSW, to enjoy the benefit at other people's expenses of gross follies, good times, sex, gambling, alcohol and rock 'n' roll? " suggested Andrew Kostopoulos.

Glancing through Mr Di Girolamo's financial records tendered at the ICAC it seems that Mr Kostopoulos was on the money.

Mr Di Girolamo was incurring hefty gambling debts, with at least $120,000 going from his bank to pay internet betting site TopSport between 2008 and 2009.

The inquiry has heard that the family of crooked Labor powerbroker Eddie Obeid acquired a third interest in AWH for the outlay of $3 million in late 2010.

Mr Di Girolamo went to St Patrick's at Strathfield with several of the sons of Mr Obeid. Since leaving school he became particularly close to Mr Obeid's youngest son, Eddie Jnr.

The inquiry had heard that Mr Obeid lobbied his colleagues extensively on AWH's behalf.

Mr Di Girolamo recently offloaded his waterfront mansion for $4.8 million and resigned as deputy chairman of Wests Tigers rugby league club. He had been pushing for the controversial Balmain Tigers redevelopment at Rozelle.

Eddie Obeid Snr has previously admitted attending a meeting in 2010 relating to the Balmain redevelopment with the planning minister Tony Kelly and Richard Pearson, the deputy director-general of the planning department.

Mr Obeid said at the time he was asked to help by a friend, Nick Di Girolamo, who was a board director. But corporate documents reveal that Mr Di Girolamo was not on the Balmain Tigers board until 2011.

After a gruelling month-long corruption inquiry, Mr Di Girolamo will have to wait several months before the final report is released.