What makes you think once you prove it is legit you get it back?? There are hundreds of horror stories that have been documented which prove you don't always get it all back. Readers Digest had a long article on this subject. This is a nightmare.
Yes, I read the Digest article about the American citizen, business owner who was on his way to Mexico to buy his father a tractor with $60,000 in cash. Stopped in the U.S. his money was seized and he had to spend $20,000 on lawyers and court costs to prove it was his.