I had a truck that I was letting a mexican citizen use while I was away - he will not return the truck to me - does anyone have information on what recourse I may have?
Common sense would be to take the pink slip (make copies of all paperwork), registration and Mexican auto. insurance papers to the police.
You must have not known that Mexicans cannot drive foreign registered cars.
If you allowed him to use your car, that may have voided the insurance (read your policy). Ask your insurance agent if the car is stolen, in that he refuses to give it back. Your U.S. policy should help if you return a police report saying it was stolen... if they don't get it back to you.
