GREENE COUNTY, Va. (CBS19 NEWS) -- The Greene County Sheriff's Office wants people to be on the lookout for some counterfeit bills that are being circulated.

The fake $20 bills have the works "prop copy" on the back.

From the front, the bills look like a normal $20, but when a special pen is used on them, the mark will turn brown.

That means the bill is not real money.

Anyone who finds one of these bills should report it to their local law enforcement agency.