As the end of his second day in the witness box neared, Jean-Claude Louis Perrottet might have been forgiven for breathing a sigh of relief.

Then came the tape recordings.

Intercepted phone conversations between the younger brother of former premier Dominic Perrottet and the now-fugitive Sydney developer Jean Nassif went off like a bomb inside the Independent Commission Against Corruption.

The calls should serve as a reminder to the public – and those politicians seeking to undermine ICAC’s work – about the grave nature of its latest probe. Operation Rosny is clearly much more than an exploration of stock-standard branch stacking or the low-level antics of a few Liberal Party apparatchiks.

The tapped calls revealed Nassif boasting about getting “the boys” to abolish a Liberal Party branch in the seat of his chief critic, former NSW police minister David Elliott. Elliott, the developer said, was a “c---” , “the worst bulldog bully” and a “lying piece of shit”.

The disgraced developer boasted of installing “f---in’ hundreds” of new party members in the Castle Hill area. Nassif also suggested giving $100,000 to one of Jean-Claude Perrottet’s brothers to support a preselection. Perrottet did not say who but Nassif was known to be in communication with one of his older siblings, Charles Perrottet.

Of his arch nemesis, the then-building commissioner David Chandler, Nassif roared: “Take a message to Charlie or to Dom – the building commissioner, we need to stop him. He’s a bully. He’s attacking me left, right and centre.

“I’ve been promised that commissioner will be f---ing stopped or changed or f---ing done something to him.”

During multiple calls with Nassif, Jean-Claude Perrottet remained calm and polite. “These people,” Perrottet replied sympathetically during one of Nassif’s rants.

He sympathised with Nassif’s plight at several points and promised to refer his concerns to his brother Charles, who the ICAC alleges had entered into a secret agreement with two other Liberal Party allies to share in a $2 million bribe from Nassif.

Jean-Claude Perrottet told the ICAC on Thursday that Nassif’s remarks were “crazy talk” and “nonsensical”. Perrottet was only talking to him because Nassif was on the books of the firm he was working for as a financial adviser, Medallion Financial.

The calls capped off a horror day for Perrottet in the witness box. Earlier, the ICAC heard that he received $25,000 from a company the watchdog believes was being used to funnel illegal donations towards a Liberal Party sub-faction known as the Reformers.

The monthly payments of $5000 were sometimes paid into his bank account; invoices had “marketing” listed in the description. Perrottet claimed he could not remember what the money was for. “I’m honestly trying to do my best here,” he offered.

He also received $80,000 directly from millionaire businessman Michael O’Hara, who is a prohibited donor due to his ownership of pubs.

There was also a cringeworthy exchange in which he claimed he was not really aware of the state’s strict donation laws at the time, despite having spent years mixing in the world of politics as a staffer and factional player.

While the payments are problematic, counsel assisting Juliet Curtin was unable to extract a concession from Perrottet that they may have been part of an illegal scheme.

Operation Rosny is the latest event in a turbulent decade for Jean-Claude Perrottet. Unlike some high-flying friends and siblings, “Claude”, as he is known by those close to him, has struggled to find his own grounding.

He landed a three-day-a-week job in the Epping electoral office of a family friend, Liberal MP Damien Tudehope, in 2018, and later his ministerial office. It was the chance for something new after a difficult few years post-high school.

But he soon started doing factional work while in the office, raising the ire of Tudehope’s chief of staff, who “blew up” because taxpayer-funded officials are banned from recruiting or renewing Liberal Party members while on the clock.

After graduating with a commerce degree from the University of NSW, Perrottet worked at Medallion Financial from January 2020 until March 2023. His employment there finished amid a blaze of damaging headlines about the absurd tactics he and other Reformers used to avoid being served summons to appear at a parliamentary inquiry into branch stacking at the Hills Shire Council.

For his part, Perrottet sat out the inquiry in Fiji, with the tab picked up by a mystery benefactor. “I went because I was not in a good place and I didn’t want to partake in what I believed was a sham inquiry,” he explained on Thursday.

During his years at Medallion Financial, Perrottet was managing several investments for Nassif, and the ICAC suggests this connection was the genesis for Nassif getting to know several Reformers.

ICAC alleges Nassif ultimately offered to pay a $2 million bribe to Jeremy Greenwood, Christian Ellis and Charles Perrottet on the understanding they would help advance his business interests in Sydney.

After severing ties from Medallion in 2023, Jean-Claude Perrottet got married at the Blessed Sacrament Catholic Church in Mosman but needed to find a job. As he did with Tudehope years before, he turned to another ally – Catholic Schools NSW chief executive and key Reformer Dallas McInerney – for assistance.

Despite being promoted in May this year to the role of head of communications and stakeholder relations, Perrottet was let go from the Catholic schools organisation as the ICAC came knocking.

The political operative-turned-financial adviser-turned-communications manager is now unemployed, aged 29, courtesy of his exploits with the Reformers.

“It’s been a pretty hectic four years,” he said on Thursday, delivering a contender for the biggest understatement of the hearings so far.