Palmer Police are warning area businesses to be on the alert for counterfeit $100 bills.

On three occasions in the Mat-Su over the last five days, people have tried to buy items at local stores and restaurants with fake $100 bills, according to Detective Sgt. Kelly Turney.

People can figure out if the bills are fake with a special pen available at office-supply stores, or by looking for the blue and red fibers, a watermark and a security stripe in the bills.

Palmer Police have notified the Secret Service and have some leads in the funny-money case, Turney said.

"We've been able to get some video and are doing interviews on how people ended up getting the bills," Turney said.

The bills were passed at a Palmer deli and Fred Meyer store and at a McDonald's restaurant in Wasilla, he said.

In all three cases, a cashier noticed that the bills didn't look or feel right, he said.

In the first two cases, the customer fled the businesses. In the third case, on Thursday, the customer stayed at the location and was interviewed by police, Turney said.

"It was a different individual (the third) time," he said.

Passing counterfeit money can result in theft charges and depending on the person's involvement in the crime, forgery charges.