I reposted, If you could sign message with the address you send such high transaction fee, you might get some tips, but I doubt about the 20 BTC
This.
There's no way to proove you are that guy, though I sure wouldn't admit to that!
Signing the address that sent the 20BTC fee would prove that you are that fool. People here call fake beggers scammers, so that would shut them up.
What does it matter? The address here in the thread corresponds to the key that signed the errant transaction.