There can be many legal reason for the difference, broken windshield replaced, tach/odometer changed, etc. You need to give the seller a chance to explain before you call the cops. If the explanations don't add up file a report of fraud. Make him prove with receipts.
broken windshield? really? he already lied to us about the car so I doubt there is any explanation other than he was trying to make money off of a car that wouldnt sell otherwise.