Remember how the FBI was instructed to blame the Anthrax attacks on Al Qaeda by White House officials in 2001?
Well, according to Washington Post reporter and Assistant Managing Editor for Investigations at The Washington Post Marilyn Thompson, the US government ordered Fort Detrick’s USAMRIID bioweapons facility to “tone down” its description of the Daschle anthrax as “weaponized.”
Moreover, scientists originally found that an electrical charge and high-tech silicon-coating were added to the killer anthrax to make it more lethal. As pointed out by anthrax expert Dr. Meryl Nass:
“If a charge were added to the spores, the charge would be expected to dissipate over days or weeks; thus the characteristics of the anthrax could have changed when inspected later. Furthermore, Dr. John Ezzell initially evaluated this anthrax in a high containment lab at USAMRIID. It was later processed before sharing with some other labs, to reduce its lethality. This processing likely changed other characteristics as well.”
Therefore, there were not only political reasons for backing away from the finding of weaponization, but there may also have been physical reasons that the weaponization might have been less apparent to scientists who subsequently studied it.
See also this.