A special pen used by a Yonkers merchant helped police catch a man passing fake bills.

According to police, at least two stores in the South Broadway shopping district got stuck with counterfeit $20 and $50 bills. Domingo Bello's son spotted the bogus cash almost immediately when a man came in to his electronics store. Bello used a special pen and saw the $20 bill was fake.

Police say the suspect left the store, but was spotted jumping into a cab. Yonkers police caught up with the man and confiscated more counterfeit cash.

Thirty-eight-year-old Clarence Ligon, of Manhattan, was arrested and is charged with criminal possession of a forged instrument. Investigators are looking into where the phony cash came from.