Early in the investigation [once it took to heart the science needed to produce the spores], the FBI appeared to endorse the latter view: that only a sophisticated lab could have produced the material used in the Senate attack. This was the consensus among biodefense specialists working for the government and the military. In May 2002, 16 of these scientists and physicians published a paper in the Journal of the American Medical Association, describing the Senate anthrax powder as "weapons-grade" and exceptional: "high spore concentration, uniform particle size, low electrostatic charge, treated to reduce clumping" (JAMA, 1 May 2002, p. 2237). Donald A. Henderson, former assistant secretary for the Office of Public Health Preparedness at the Department of Health and Human Services, expressed an almost grudging respect: "It just didn't have to be that good" to be lethal, he told Science.
As the [criminal] investigation dragged on, however, its focus shifted. In a key disclosure, U.S. Attorney General John Ashcroft revealed in August 2002 that Justice Department officials had fixed on one of 30 so-called "persons of interest":Steven J. Hatfill, a doctor and virologist who in 1997 conducted research with the Ebola virus at the U.S. Army Medical Research Ins ute of Infectious Diseases in Fort Detrick, Maryland. (Hatfill has denied any involvement in the anthrax mailing.)