Police say the fake tickets are getting better and better.
Modern technology is making it easier and easier to make high quality copies of event tickets, and some Bears fans are being victimized.
Perry Griffith thought he had bought real Bears tickets on Craigslist, and he even got inside Soldier Field, but when he arrived at his seats, someone else was sitting there.
"The gentleman says, 'Actually we are the seat holders, and you're the third people to come to these seats asking to sit here,'" Griffith said.
Police say it's almost impossible to tell if an ad on Craigslist is legitimate with a number of sophisticated counterfeiters working the Chicagoland area.
Griffith's tickets looked legit.
"The numbering the bar codes were different for each ticket. I mean, whoever went through this made a lot of effort," Griffith said.
Area Central commander Eugene Roy was hesitant to talk about police methods, but admits it's a big problem.
"We're seeing dozens. There are stacks of 'em that com in after each game, from different gates and at the ticket booth and from security," Roy said.
Police have been engaged in an active investigation since the beginning of the Bears season.
"We've make approximately 10 arrests of individuals involved in producing counterfeit tickets and selling counterfeit tickets," Roy said.
Police urge fans never to pay cash to private sellers for tickets.