Some 13 KPMG executives, past and present, were grilled by the powerful federal panel with oversight of the corporate regulator in Canberra on Friday.
The committee took no prisoners as it questioned timelines, procedures, documents and the firm's level of regret over events that erupted into public consciousness on May 29.
It was left to Greens senator Barbara Pocock to underscore the inquiry's importance when she asked why the public should trust consultancies, given an earlier scandal involving PwC.
"The big four accountancy firms are strong and big companies ... that create careers for young people," KPMG's former chief executive Andrew Yates said.
"They're all focused on serving the public good.
"They're big, but they make mistakes."
In 2023, PwC was found to have shared confidential federal government tax information with prospective clients.
It was banned from new contracts for more than a year and ended up selling its government advisory business for $1.
KPMG, which has 297 active federal contracts worth $653 million, allegedly misused confidential board papers to win new audit contracts and mistreated a whistleblower who raised concerns.
While yet to face any major penalty, KPMG is already under a three-month moratorium on new finance department work and has been referred to the National Anti-Corruption Commission by Senator Pocock.
During Friday's hearing, the committee was told Lendlease, the construction company at the centre of the audit leak, was seeking a new auditor after 68 years as a KPMG customer following a breakdown of trust.
Mr Yates, who resigned on May 29 over the treatment of the whistleblower, was also forced to defend himself.
"I don't see myself as a bad apple," he told the committee.
"I see someone who took accountability for things that went wrong and nor do I see the firm to be full of bad apples.
"We're a large, complex organisation and we're fallible."
KPMG chair Martin Sheppard said the events did not reflect a pattern of behaviour at the firm.
Committee chair Deborah O'Neill had former KPMG audit head Julian McPherson read a 2024 statement from the whistleblower into Hansard, outlining their concerns.
"I have seen a number of actions taken by individuals that are quite clearly not up to the ethical standards of KPMG, or the expectations of regulators, governments, or the public at large," he read.
"It is KPMG's toxic culture and its thirst for improved partner remuneration at all costs that have resulted in them (their concerns) not being listened to or acted upon."
Later, Mr Sheppard faced a further committee blowtorch over his decision to deny it access to internal documents, citing confidentiality, professional privilege and the risk of prejudicing the administration of justice.
Senator O'Neill told him it was "outrageous", given the committee dealt with sensitive and privileged documents all the time.
"You have insulted us by not providing them," the Labor senator said.
"We just don't trust you any more."
Senator O'Neill has already taken advice from Senate clerk Richard Pye, who says the parliament could investigate KPMG for potential contempt.
Mr Martin said while he and the committee might "not agree on this matter", he had done his best to address the needs of all stakeholders.
"This has probably been amongst the most difficult decisions I've made in my executive career," he said.
During the hearing, the number of people watching the inquiry on the committee's YouTube channel peaked at more than 6300, from 850 when it began after 8.15am.
11°C