My dad owns a liquor store. A customer came in and brought in a check, the name, address and the rest of the information completely matched the information on the I'd, he cashed him out for 4000$ his son comes back a couple months later and let's my dad know that it was probably his dad because they live together and share the same name. His son had went to court and said that it was not him that cashed the check and he won the case and my dad lost 4000 without even being notified. What can my dad do right now?