(CBS) – Two brothers are accused of trying to bilk the state of millions of dollars in gasoline taxes that consumers paid at the pump.

CBS 2’s Brad Edwards reports.

Naveed Ahmed and Asif Waheed operated a now-shuttered tax business that did not shell over what was owed the stat, authorities says. They helped short the state of $5 million in gas taxes, the Illinois Attorney General’s Office says.

That office’s crackdown on tax fraud to date has netted $75 million the state was shorted.

“At the beginning i don’t think it would prove to be as widespread as it has proven to be,” Illinois Attorney General Lisa Madigan says.

She says authorities have noted a great deal of compliance following indictments.

Naveed Ahmed of Arlington Heights and his brother, Chicago resident Asif Waheed, each pleaded guilty Friday to multiple counts of wire fraud, mail fraud and preparing fraudulent tax returns, according to a release from Madigan’s office.

Between 2007 and 2009, the brothers allegedly conspired with owners of gas stations in Chicago, Cicero, Homewood and Joliet to bilk the state out of more than $5 million in sales tax revenues, authorities say.

The brothers, arrested in 2011, accepted a plea deal and cooperated with investigators in exchange for a sentence of two years of felony probation, authorities said.

The owners of the gas stations also pleaded guilty on other charges and have repaid the state more than $5 million in back sales taxes.

Contributing: Sun-Times Media Wire