His digital identity was compromised 'for ever', I don't know if we will be able to prove that he is the real master-p.
If he claimed to be the real master-p, someone could probably send a letter to master-p's house with a code or something inside, and then ask master-p to PM the sender the code he received in the mail, to verify that he is indeed the original master-p.
He could keep it to himself.