I don't have time for a detailed answer right now. Let me just say that I don't think that "al-Qaeda was behind it"; I think the evidence indicates that some country was behind it, probably Iraq. That country may have used al-Qaeda agents to deliver the anthrax, however. I do think that it's conceivable that some U.S. scientist sold them the anthrax from American stock, so this isn't entirely inconsistent with there being some domestic angle to it.
There's a great deal of evidence connecting the 9/11 terrorists and Iraq to anthrax (you've seen it all, so I won't repeat all the details -- the proximity between the hijackers' apartments and AMI, as well as the connection with the rental agent; Mohamed Atta's meeting with an Iraqi agent and his investigation into cropdusters; Alhaznawi's apparent infection with cutaneous anthrax; the timing, so close to 9/11; the known Iraqi interest in biological weapons and, in particular, anthrax; the "weaponization" of the anthrax, which is now said to be better than the U.S. ever achieved; the handwriting on the letters; as well as many other facts).
Admittedly this evidence is circumstantial. However, in contrast, I know of no actual evidence for, say, the Rosenberg/Greenpeace theory or for some other connection with U.S. scientists. (As far as I know, the Milwaukee scientist didn't work with anthrax; he was a research chemist in explosive ordnance systems. I know that the date of the police report in Milwaukee is peculiar, but that's not much of a link.)
If it was a domestic scientist, here's a question: How did he fill the envelopes? This anthrax is highly weaponized; it's uncharged and scatters veryeasily. Filling the envelopes without contaminating everything around would be quite difficult. [Also, if this anthrax really is more weaponized than the U.S. ever made, where did he get it? I don't believe he could have prepared it himself in a makeshift lab in his house.]
Well, this turned out to be a longer post than I'd planned. I'd like to add that you have an excellent web site, with a great deal of good research on it. I just don't agree with your conclusion :-).
I have a section describing how it was done. It's HERE.
But, personally, I think the guy used his lab at work. I think he has unlimited access to a sophisticated lab somewhere in Central New Jersey, probably in a pharmaceutical company, hospital or university.
Shouldn't you have asked "If it was al Qaeda, how did they fill the envelopes?" It would be much easier for a working American scientist to fill the envelopes than some al Qaeda member hiding out in a motel room.
The evidence seems to indicate that the scientist grew the anthrax himself (from an initial supply furnished to him by someone who previously worked in the biodefense area - like the "Milwaukee scientist). He quickly prepared the first mailing of Sept. 18 from anthrax supplies on hand, then grew more anthrax over the next three weeks and more thoroughly refined it for the second mailing of Oct. 9.
I don't think weaponizing anthrax is as difficult as some "experts" believe. There's a link on my site to an Apr. 27 article by the Weekly Standard that describes in detail how there are ways to "weaponize" anthrax that are very simple. The "experts" are just thinking about the complicated ways that the U.S. government last did it back in the 1960s. There have been lots of scientific advancements since then. And there are "experts" who believe it can now be done in a garage with $2,500 worth of equipment.
All the so-called "proof" that al Qaeda was behind the anthrax mailings is really only proof that al Qaeda was investigating ways to make bioweapons, they were building labs to make bioweapons, and they are really nasty guys would would use bioweapons if they got the chance. And, too, some 9-11 al Qaeda members got sick with sores and coughs last June, but they were all DEAD for a week before the first mailing, and DEAD for a month before the second mailing.
If you look for evidence that al Qaeda are creepy, nasty guys who would kill you if they got the chance, you'll find plenty of it. But if you look for evidence that they were behind the anthrax mailings, you won't find any. IMO
Ed Lake