Let's start with the anthrax in the letters to Sens. Tom Daschle and Patrick Leahy. The spores could not have been produced at the U.S. Army Medical Research Institute of Infectious Diseases, where Ivins worked, without many other people being aware of it. Furthermore, the equipment to make such a product does not exist at the institute.
Information released by the FBI over the past seven years indicates a product of exceptional quality. The product contained essentially pure spores. The particle size was 1.5 to 3 microns in diameter. There are several methods used to produce anthrax that small. But most of them require milling the spores to a size small enough that it can be inhaled into the lower reaches of the lungs. In this case, however, the anthrax spores were not milled.
What's more, they were also tailored to make them potentially more dangerous. According to a FBI news release from November 2001, the particles were coated by a "product not seen previously to be used in this fashion before." Apparently, the spores were coated with a polyglass which tightly bound hydrophilic silica to each particle. That's what was briefed (according to one of my former weapons inspectors at the United Nations Special Commission) by the FBI to the German Foreign Ministry at the time.
Another FBI leak indicated that each particle was given a weak electric charge, thereby causing the particles to repel each other at the molecular level. This made it easier for the spores to float in the air, and increased their retention in the lungs.
Aside from being reminded that I really don't know enough about anthrax and anthrax production to have an educated opinion about the case, does that last bit make any sense? Wouldn't a charge on the particles dissipate while the letters were in transit?
Link from The Agitator.