Send an email to Josh, and give him a deadline to contact you to work out a repayment plan. Let him know that if he decides to ignore the request by the given deadline that you will contact the FBI. Provide him with the information that you have about him i.e. his home address, phone number, etc. In the email state the legal presidence for FBI involvement i.e. interstate fraud, theft, etc. Ensure that he knows that interstate fraud is a federal offense and is a felony. If this does not get his attention, then he deserves what is coming to him.