You should check the law in your state, but generally this is a third party check and there is no criminal recourse. Any recourse is civil only. Your cousin did not write or issue the check. A check cashing business takes a risk cashing any third party check and that is a risk of their business.
There was a fraud conducted on your cousin. He needs to go to the US attorney and report this. This scam is a federal crime as it is fraud on a US insured bank.

