This caller is using counterfeit checks for usually the same amount and sending it to victims of their scam. Here is a message I am sending to other victims:
This check is a counterfeit check from a scam by a person unknown at this time. Please let the victim know they need to contact their local Police Department Financial Crimes and to file a complaint with the FBI. The link I have found is:
http://www.ic3.gov/default.aspx
Also the FTC has a link on their website to file a complaint: https://www.ftc.gov/
How the victim was notified; Craigslist, Facebook, or other texting.
The instructions from the scam artist, how to give the money back or ship the sold item.