(28.12.2001) The army biological and chemical warfare unit at the Dugway Proving Ground, about 80 miles southwest of Salt Lake City, Utah, may well be the source of the weapons-grade anthrax sent to Senators Tom Daschle and Patrick Leahy. Scientists at Dugway grew and processed spores deriving from the Ames strain—the strain that appeared in all the letters sent to media outlets and Congress.

The spores had been carefully milled to produce the size most effective in spreading the deadly bacteria, between one and three microns.

The existence of the secret army program was first revealed by the Baltimore Sun in an article published December 12. Until then, US officials, including those investigating the anthrax attacks, had maintained that the American military stopped producing germ warfare materials in the late 1960s, before the signing of an international treaty banning the development of such weapons.