The government indirectly acknowledged that it misled the public through some of its officials about the 2001 anthrax attacks. As it turns out, the powder was not in fact weapons-grade, coated with a special silica substance to make it easier to inhale, but was just naturally fine enough. It is unclear though whether it was intentional disinformation, and the FBI will likely not elaborate.

Federal Bureau of Investigation officials on Monday, at the Bureau's headquarters, organized a carefully planned press conference which laid out the evidence against Dr. Bruce Ivins, the U.S. Army researcher who killed himself after being targeted by investigators into the 2001 anthrax attacks. Backed by a small army of scientists, the FBI says that it Ivins was the only one of the around 100 people who had access to the specific anthrax strains used in the attacks who was not cleared in the investigation.

Although the press conference at FBI headquarters has highlighted the important scientific advances in the course of the investigation, which tracked the powder to a flask of anthrax identified as RMR-1029 at the U.S. Army Medical Research Institute of Infectious Diseases at Fort Detrick, Md., it also highlighted the many mistakes done by the investigators.

The FBI could have sniffed Ivins out earlier had it not destroyed in a crucially bad decision a sample sent by him in 2002. The FBI destroyed the first anthrax samples submitted because Ivins didn't prepare them according to the protocol spelled out in a court order. This delayed identification by years, probably, as the FBI managed to obtain other samples in December 2003 and April 2004. The 2003 sample did not link Ivins to the attack, for reasons yet unknown, but the second one did.

The conference left most questions unanswered. Some anthrax victims could not be linked to the anthrax-laced letters, and several scientists remain skeptical of the evidence against Ivins, which, as revealed until now, is mainly scientific and circumstantial. What the FBI actually claims is that based on the evidence so far, Ivins is the only one who could have done it, in theory.