Peter,
Have you figured out who "Country Joe" is? Is doesn't take the CIA or a forensics lab to figure it out.
Look at the language in the MP3 lunatic ravings. Look closely at the vernacular. He has given himself away. There is only one place in the world where this language lines up. He is your customer. You have his address. You know where he lives. Look closely. I am sure you have already figured it out.
Drunk people leave sloppy trails.