Police are investigating reports of counterfeit 50-dollar bills being passed at businesses in St. Joseph County.

One Granger-area business owner discovered what appeared to be a legitimate 50-dollar bill was actually an altered 10-dollar bill.

The money even passed a counterfeit detection pen test because the original currency was genuine.

Indiana State Police say business owners should examine security features, including the embedded security thread, rather than relying solely on detection pens.

The St. Joseph County Police Department is investigating, and anyone who suspects they’ve received counterfeit money should contact police or their bank.