anthrax

"Soon after I informed Bowman [a high-level official in the FBI who deals with terrorism and counterterrorism] the FBI authorized the destruction of the Ames cultural anthrax database," Professor Boyle said. The Ames strain turned out to be the same strain as the spores used in the attacks. The alleged destruction of the anthrax culture collection at Ames, Iowa, from which the Fort Detrick lab got its pathogens meant that there was no way of finding out which strain was sent to whom to develop the larger breed of anthrax used in the attacks. The trail of genetic evidence would have led directly back to a secret government biowarfare program. "Clearly, for the FBI to have authorized this was obstruction of justice, a federal crime," said Boyle.

...the New York Times revealed the technology behind the letter to Senator Daschle. [The anthrax used was] a trillion spores per gram, [refined with] special electro-static treatment. This is superweapons-grade anthrax that even the United States government, in its openly proclaimed programs, had never developed before. So it was obvious to me that this was from a U.S. government lab. There is nowhere else you could have gotten that.