You can contact your local post office and put an inquiry on the M.O. If it's cashed, you'll recieve front and back photocopies of it, showing who cashed it.
Takes a while, though.
If it's determined that it's lost, you can get a refund.
As far as fraud goed, here's a link to the USPS Inspection Service:[url]http://www.usps.com/postalinspectors/fraud/[/url]