I would call the 3 different credit bureaus and have them put a "Red Flag" on sons SS#! Let them know the details and see what service they can provide. I'd also call the credit card company and see if you can get a copy of the original credit card application with signature of your 9 y/o sons on it! Also, get confirmation where these statements were being mailed too. I would also call the police and get them involved. Then I would pull all the info from these bureaus and go from there!