CHICAGO (CBS) – Feeling hosed at the gas pump? So is the State of Illinois. Multiple agencies are finally starting to reap the rewards of a multi-year investigation targeting gas station owners who withhold sales tax revenue.

So far, the state’s collected $72 million.

A Lincolnwood Marathon, once a ‘mom and pop’ gas station, run by Adam and Renata Safin, is the latest charged culprit. State officials said the couple bilked $237,000 in sales tax revenue from the state between 2009 and 2011.

They’re one of 35 cases brought against sales tax-evading gas station owners.

“Are you surprised how many are doing this?” asked CBS 2′s Brad Edwards.

“It’s a shocking number,” said Attorney General Lisa Madigan. “It’s shocking.”

Bhavesh Ganhdi, a gas station owner in Kane County, will be one of the first to be sentenced this week, for allegedly bamboozling more than $250,000.

“Is this their dirty little secret that you’ve uncovered?” asked Edwards.

“We have found is that this is a pervasive what we’re calling an ‘under reporting scheme,’” said Madigan. “To learn that you’re paying these prices and the amount that you’ve had to pay toward the sales that’s supposed to go to the state has been staying in the pocket of the gas station owner — that’s the crime and that’s what we’ve been going after.”

Madigan’s office has worked in concert in the Department of Revenue in the investigation that was instrumental in the formation of a new law for sales tax evasion.

The new sales tax evasion law extends the statute of limitations from 3 years to 5 years, to match other tax evasion statutes. It also imposes tougher prison terms for those convicted of sales tax evasion.