Secretary general of the Association of Public Accounts Hlomani Chauke told the paper that the suspected hit on forensic auditor Lawrence Moepi was just "the tip of the iceberg".
Moepi, the director of forensic company SizweNtsalubaGobodo was shot dead at the company's office in Houghton last week.
"Nowadays, these kinds of attacks are happening to people who are unravelling corruption and mismanagement of public and private money," Chauke was quoted as saying.
He said auditing companies were vulnerable, because corruption was widespread.
Chief executive of the Independent Regulatory Board Bernard Agulhas told the paper that the lives of many auditors were at risk.
"While we are trying to strengthen the independence requirements for auditors as an oversight body, those that are truly independent now have their lives at risk. If the life of an auditor is threatened, it means the independence of auditing is threatened," Agulhas said.
He said while the board could not offer physical protection for auditors, they encouraged them to work with the police.
Moepi was reportedly working on several investigations.
In his capacity as PricewaterhouseCoopers forensic services director, Moepi testified in the fraud trial of former Scorpions official Geoffrey Ledwaba.
Moepi's killing was also condemned by the Association for the Advancement of Black Accountants of SA (Abasa) on Monday.
"We strongly condemn such cowardly acts where members of our profession are threatened and ultimately killed for just performing their job," it said in a statement.
Abasa appealed to its members to continue their work "without fear or favour for the sake of our country, even when under threat".
"The profession has lost a prominent, well-respected leader within the forensic audit space."
SA Institute of Chartered Accountants (Saica) CEO Matsobane Matlwa said in a statement: "The institute, on behalf of the chartered accountancy profession, deeply regrets the unfortunate event which prematurely took the life of one of our esteemed members."
He said he had offered the institute's support to the management of SizweNtsalubaGobodo in addressing the circumstances behind the murder.
Saica, Abasa and Cosatu extended their condolences to Moepi's family, friends and colleagues.