(CBS) – The Cook County Recorder’s Office handles more than a million documents a year, making it the largest office of its kind in the country

But some of those filing documents are criminals who try and take over homes illegally.

As CBS 2’s Mike Puccinelli reports, sometimes they are so brazen they even try and oust people from occupied homes.

One elderly woman wants to tell her story.

What she can’t believe is how, in July, a fraudster actually tried to illegally take over her home. She knew something was wrong when her son no longer could get in the front gate.

“He called me and said, ‘I can’t get in,’” says the woman, who doesn’t wish to be identified. “I said, ‘What do you mean you can’t get in the gate?’”

It turns out, the locks had been changed. Then the situation got worse when the fraudster attempted to change the locks on her front door. She saw the crime in progress and called for help.

But when police arrived, the fraudster presented documents claiming he was the owner of the building.  All the while the real owner watched from her upstairs window.

He was so convincing and the documents appeared to be authentic, so he wasn’t arrested until last month. Despite the rather sophisticated means of hijacking homes, police investigators say there’s really no hiding what the fraudsters are.

“Thieves, burglars and financial parasites,” says Sgt. John Lucki, financial crimes commanding officer for the Chicago Police Department.

Victims trying to force a fraudster out of a hijacked property can rack up expenses, he says.

“It can pretty much tie up your financial existence,” he says.

That’s why the Cook County Recorder’s office is stepping up its fraud-detection efforts by actively promoting its free property-fraud alert system. It notifies an owner when a document is recorded against their property.

Cook County Recorder Karen Yarbrough says it’s the best way of fighting back against a crime that is growing in Chicagoland.

The city treasurer of Chicago actually is another victim of this crime.

Yarbrough also was astonished to find that a mortgage had been taken out on her home. She thinks that was likely a simple mistake.