From one of the WSJ articles I read which highlights some of my concerns with the Ivins case:
Silicon was used in the 1960s to weaponize anthrax. Through an elaborate process, anthrax spores were coated with silicon to preventing them from clinging together so as to create a lethal aerosol. But since weaponization was banned by international treaties, research anthrax no longer contains silicon, and the flask at Fort Detrick contained none. Yet, the anthrax grown from it had silicon, according to the US Armed Forces Institute of Pathology. This silicon explained why when the letters to Senators Patrick Leahy and Tom Daschle were opened, the anthrax vaporized into an aerosol. If so, then somehow silicon was added to the anthrax. But Dr. Ivins, no matter how weird he may have been, had neither the set of skills nor the means to deliberately attach silicon to anthrax spores. At minimum, such a process would require highly-specialized equipment, such as a jet mill, that did not exist in Ivins’ lab– or, for that matter, anywhere at the Fort Detrick facility. As Richard O. Spertzel, a former bio-defense scientist who worked with Ivins, explained, the lab didn’t even deal with anthrax in powdered form, adding "I don't think there's anyone there who would have the foggiest idea how to do it." So while Dr. Ivins’ death provided a convenient fall guy, the silicon content still had somehow to be explained.
The FBI’s answer was that the anthrax contained only traces of silicon and those, it theorized, could have been accidently absorbed by the spores from the water and nutrient in which they were grown. No such nutrients were ever found in Ivins’ lab, nor, for that matter, did anyone ever see Dr. Ivins attempt to produce any unauthorized anthrax (a process which would have involved him using scores of flasks.) But since no one knew what nutrients had been used to grow the attack anthrax, it was at. least possible that they had traces of silicon in them which accidently contaminated the anthrax.
Natural contamination was an elegant theory that ran into problems after Congressman Jerry Nadler pressed FBI Director Robert S. Mueller III in September 2008 to provide the House Judiciary Committee with a missing piece of data: the precise percentage of silicon contained in the anthrax used in the attacks. The answer came seven months later. According to the FBI lab, 1.4% of the powder in the Leahy letter was Silicon. "This is a shockingly high proportion," explained Dr. Stuart Jacobson, an expert in small particle chemistry. "It is a number one would expect from the deliberate weaponization of anthrax, but not from any conceivable accidental contamination." Nevertheless, in an attempt to back up its theory, the FBI contracted scientists at the Lawrence Livermore National Labs in California to conduct experiments in which anthrax is accidently absorbed from a media heavily-laced with silicon. When the results were revealed to the National Academy Of Science in September 2009, they effectively blew the FBI’s theory out of the water. The Livermore scientists had tried 56 times to replicate the high silicon content without any success whatsoever. Even though they added increasingly high amounts of silicon to the media, they never even came close to the 1.4 percent in the attack anthrax. Most results were indeed an order of magnitude lower, with some as low as .001 percent. What these tests inadvertently demonstrated is that the anthrax spores could not have been accidently contaminated by the nutrients in the media. " If there is that much silicon , it had to have been added, " Jeffrey Adamovicz, who supervised Ivins work at Fort Detrick, wrote to me. He added that the silicon signature in the attack anthrax could have been added via a large fermerntor– which Battellle and other labs use" but "we did not use a fermentor to grow anthrax at USAMRIID [and] We did not have the capability to add silicon compounds to anthrax spores."
If Dr. Ivins had neither the equipment or skills to weaponize anthrax with silicon, then some other party, with access to the anthrax, must have done it. Even before these startling results, Senator Leahy had told Mueller , "I do not believe in any way, shape, or manner that [Ivins] is the only person involved in this attack on Congress." So, even though the public believed that the Anthrax case had been closed more in 2008, the FBI investigation was back to square one in late 2009.
