spammer update...
I got a message from the guy whose name has been associated with the spams, and he said he has "done some research on the situation because [he] personally [is] receiving quite a few unsolicited messages as well."
I wrote back with the response: "You've done some research? And what has this research concluded? Your name is on these spams!"
Of course, no response. If I don't hear back, I think I'll just forward the whole thing to the authorities and let them handle it, no matter what the response.