By Joby Warrick

In late October 2001, lab technician Terry Abshire placed a tray of anthrax cells under a microscope and spotted something so peculiar she had to look twice. It was two weeks after the country's worst bioterrorism attack, and Abshire, like others at the Army's Fort Detrick biodefense lab, was caught up in a frenzied search for clues that could help lead to the culprit. Down the hall, Bruce E. Ivins, the respected vaccine specialist, was looking, too.

Abshire focused her lens on a moldlike clump. Anthrax bacteria were growing here, but some of the cells were odd: strange shapes, strange textures, strange colors. These were mutants, or 'morphs,' genetic deviants scattered among the ordinary anthrax cells like chocolate chips in a cookie batter.

Unknowingly, Abshire had discovered a key to solving the anthrax case. But it would take nearly six years to develop the technology to allow FBI investigators to use it. ....