Okay, I'll revise my new conclusion slightly. I don't know if this was a rightwing guy targeting leftists, or a leftist trying to blame it on the rightwing. I don't know if it was a Jew trying to blame an arab, or whether it's a sleeper trying to kill leftists or simply cause trouble.
But, I don't think this was a terrorist here on a visa. I think our anthrax terrorist is someone who has been here a long time, and more than likely got the anthrax from an American laboratory. Leahy makes no sense as a target unless you really hate Democrats or want to make it look as if you do.
Al-Qaida isn't after subtle targets like Leahy.
It's, also, noteworthy that there have been simultaneous anthrax attacks in other countries that most Americans can't even find on a map. A newspaper in Pakistan received an anthrax letter, anthrax attacks in India, etc. I think this is international terrorism in response to a Muslim call to jihad and related to the anthrax attacks in the U.S.