On September 18, 2001—a week after the September 11 al-Qaeda terrorist attacks on the Pentagon and World Trade Center—letters containing anthrax spores were sent to Tom Brokaw at NBC news, Peter Jennings at ABC news, Dan Rather at CBS news, and to the editor of the New York Post. The letters passed through a mail-sorting facility in Hamilton, New Jersey. Two employees at the New York Post, two NBC workers, an employee at CBS, six local postal workers, and a baby who had visited ABC all became ill. The illnesses were not immediately recognized as anthrax, but the victims received medical treatment and recovered.

Two weeks later, in early October 2001, Robert Stevens—a photo editor at the Sun (a tabloid newsmagazine) in Boca Raton, Florida— died from an undiagnosed disease. Two other employees in the building also...