An illegal tactic at that. In the US at least, debt is a civil matter and not criminal. Anyone making threats of arrest over some old bill or a likely false ''hot check'' claim is a liar and breaking federal law. Ditto for posing as law enforcement or implying in any way that police will take an interest in the matter.
This may be the usual dirty debt collector within the U.S. or a fake collector from South Asia. Try to get a business name and share it with the readers. By federal law this name cannot be withheld. If the collector is domestic you can sue them yourself and your legal fees will be extracted painfully from the offender's hide.
Learn how to exercise your FDCPA rights as an alleged debtor at FTC-dot-gov. See also if your state laws are stronger.