Allegations Liberal Party operatives sought cash from Jean Nassif in exchange for political outcomes are being investigated by the Independent Commission Against Corruption.
Nassif fled to his ancestral homeland Lebanon in late 2022 with a NSW Police arrest warrant out for him and his building empire Toplace collapsing owing billions of dollars to creditors.
He is set to appear at the inquiry on September 4 via audio visual link from Lebanon, the commission confirmed to AAP.
Earlier, former NSW Building Commissioner David Chandler told the commission he was threatened by Nassif after halting progress on one of his company's projects over potential defects.
He said he inspected the Skyview development in Castle Hill in April 2021 after being contacted by concerned parties, eventually issuing a prohibition order on the project to get an independent engineer to certify it.
The order prevented a certificate of occupancy from being granted, delaying the settlement of apartment sales in the complex.
Nassif then began leaving threatening voice messages, Mr Chandler said.
"It was essentially, 'Don't you hurt my project, or I'll hurt you,' or something along those lines," he said.
Nassif allegedly sent numerous text messages pleading for him to help him get his occupancy certificate followed by the praying emoji.
Mr Chandler said the phone correspondence came after he stopped agreeing to meet Nassif in person.
He said Nassif "really laid into" him during their first and only face-to-face meeting in May 2020 over defect concerns in another of Toplace's projects.
"He just said ... 'Don't think you can just come in and step all over me because I'm an important person'," Mr Chandler recalled.
"He was overbearing and loud. I'm not going to say he did anything physical, but certainly he was very animated in his expression."
Mr Chandler told the inquiry that in a subsequent meeting with representatives from Toplace, they said they received an email asserting Mr Chandler would lift the prohibition order if $5 million was paid into a nominated trust account.
But he said he called their bluff after urging them to report the apparent extortion attempt to NSW Police.
"That was just a disruption technique ... basically to unsettle me," Mr Chandler said.
He was cross-examined over this "shakedown meeting" by the lawyer for Sharangan Maheswara - a person of interest in the inquiry and a then-executive at Toplace.
Sebastian De Brennan asked if Mr Chandler conceded that by the time of this meeting, there was an "agreed methodology" for the project to move forward and for his prohibition order to be lifted.
"I don't see how that changes my evidence," Mr Chandler replied.
Mr Chandler resigned from his role in 2022 after "reading the tea leaves" that then-Fair Trading minister Eleni Petinos might announce she had lost confidence in him.
It followed a series of "unsettling" events, he said, including one where he was accused and then cleared of misconduct after a covert video of him was leaked to News Corp paper The Australian.
He said there were rumours being spread about him that he was accepting bribes.
Representatives from Toplace were behind this "intentional campaign" to push him out of his role, he claimed.
However, he said he agreed to withdraw his resignation after Ms Petinos was sacked by then-premier Dominic Perrottet over an "unrelated matter".
The incoming minister Victor Dominello urged him to reconsider his resignation, as did the premier, Mr Chandler said.
While fronting the commission last week, Ms Petinos said she had been told by party operatives, including Mr Perrottet's factional power-broking brother, Charles, that Mr Chandler was "dodgy".
She agreed, in retrospect, her office may have been being used by these operatives to push Mr Chandler out.