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(CBS) — The Cook County Assessor’s crackdown on property tax cheats has begun.

He tells CBS 2’s Pam Zekman that he’ll collect $20 million by the end of the year.

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It took two years for the Assessor Joseph Berrios to get new laws he needed for this action — an effort that began after a 2 Investigators report in 2011 on one of the biggest violators.

His name is Dominic Santoro, and he was not happy to see Pam Zekman back in 2011. Santoro had a homeowners exemption at his home  in South Barrington, and eight more homeowners exemptions on apartment buildings in Rosemont.

That’s a problem. You’re only entitled to one, Cook County Assessor Joseph Berrios says.

Zekman warned Santoro three years ago that he owed the assessor’s office $87,000 to make up for the tax breaks he got over 10 years with all those exemptions.

Now, under a new law that applies only to Cook county, the assessor can only go back to collect six years of undeserved tax breaks. But the assessor can also charge anyone with three or more erroneous exemptions 10 percent interest a year and 50 percent in penalties on the unpaid taxes.

For Santoro, that means he now owes $111,533.

“That’s absolutely huge and thank you for the tip,”  Berrios tells Zekman.

CBS 2 reached Santoro by telephone last week. He said he’s “working on it,” when asked what he will do.

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Berrios also is going after Daniel Cuevas, whom he says has erroneous homeowners exemptions at seven houses and five lakefront condos that saved him $61,152 in property taxes. The assessor says with interest and penalties Cuevas now owes $120,300.

The 2 Investigators went to question Cuevas outside the assessor’s office, but he refused to comment and fled across Daley Plaza.

In another case,  a now-former assessor’s office employee allegedly helped a property owner in her forties get tax freezes that you’re only entitled to when you are 65.

That employee, Dionne Cooper, was hired under a different administration and fired by Berrios after she was charged with theft and official misconduct in a now-pending criminal case. She is charged with splitting the proceeds of fraudulent tax breaks, apparently with another co-conspirator.

The assessor says records show Cooper also helped Nicole Chatman improperly get senior freezes and homeowners exemptions at six homes. Now, the assessor says Chatman owes $81,897 from her improper tax breaks. With interest and penalties, her total tab is $156,007.

The 2 Investigators went to question Chatman about her exemptions at her Calumet City hair salon.  Chatman said she thought the help she got from the assessor’s office was legitimate and she is innocent of any wrongdoing.

But, the assessor is not buying that argument.  And he warned property owners: “I intend to make sure that this office goes after every potential tax fraud cheat.”

Under the new law, the assessor can place a lien on the property belonging to those who can’t or won’t pay.  That means when the owner sells the property, the county gets back the money from the proceeds. The recovery program has already resulted in a total of $4.7 million billed to taxpayers and $2.7 million collected, Berrios said.

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You can check out property exemptions on the websites for the Cook County Assessor and the Cook County Treasurer’s office.