I thought all along that it was someone within her organization or on the fringes of it who were the likeliest suspects. She probably knows what she knows more from the criminal side than from the govt side. Note her ant-govt spin.
This also fits the fact that Dems were targeted and warned to get treated, since they were the ones who needed to be activated. Also, Leahy was a leader of the Judiciary Committee, who had to approve the treaty that she and her group was pushing. It all fits together so nicely!
Interesting possibility. Of course, it's equally if not more likely that the perp figured a good anthrax scare would increase funding for the government/military biowar program he worked for.