CHAMPAIGN, Ill. (WAND) - Reports of fake money circulating in the Champaign area led to police launching an investigation. 

Officers said counterfeit currency reports often included someone showing a washed or bleached $10 bill and presenting it as a $100 bill. They said an employee in one store noticed the watermark on one of these bills was of Alexander Hamilton and not Benjamin Franklin, then denied a purchase. 

Police said offenders in these cases are often trying to make a purchase with a fake $100 bill in order to get as much real currency in return as they can. The money is circulated when it's passed through the hands of several people, then is spent by making small purchases at stores. 

"Police are encouraging all businesses to review the security features of U.S. Currency and how to authenticate money," a press release from Champaign police said. "Additionally, be wary of unknown persons who attempt to make small purchases with large denominations, ask for bills to be traded out or make unusual requests for change."

Police said people can check authenticity of money by holding it up to a light and looking for a watermark of the bill's face image. If it's authentic, the images should match. Looking through a light should also reveal a thin vertical stripe with text of the bill's denomination. 

More details about security features of U.S. currency area available online here.

Police want anyone who suspects the use of counterfeit currency to call Champaign police or the local U.S. Secret Service Office. The Champaign Police Department can be reached at (217)351-4545, and anonymous tips can go to Crime Stoppers by calling (217)373-8477. 

Crime Stoppers accepts tips online at this link or through the "P3 Tips" mobile app.Â