Auditor General Frank Mautino is under federal investigation, according to a statement from his spokesman.
The spokesman says Mautino is cooperating with the U.S. Attorney's office. He says because it's ongoing, he cannot comment further.
It comes in response to a report in the Illinois Times that Mautino's former campaign workers have been subpoenaed.
Subpoenas don't always lead to charges.
Mautino, a former Democratic legislator, is under scrutiny for what critics describe as excessive and suspicious campaign spending. The state elections board is looking into his campaign finance reports.
Republican lawmakers say it leaves them questioning the integrity of Mautino's state audits.
He's been Illinois government's fiscal watchdog since January.
