The anthrax scare unfolded shortly after the September 11, 2001, terrorist attacks on the World Trade Center and the Pentagon. When news first broke that anthrax-laced letters were received at East Coast media outlets and U.S. congressional offices, there were fears that the spreading of the infectious bacterium was linked to the 9/11 attacks. But the investigation later pointed toward a domestic perpetrator, still unknown in mid-2005.

According to a report from the office of Homeland Security, the anthrax events began on October 2, 2001, when an infectious disease doctor in Palm Beach County, Florida, reported a suspected case of inhalation anthrax. That diagnosis was confirmed by the Centers for Disease Control (CDC) on October 4 and the information was released to the public, rattling the nerves of an already jittery nation. On October 5 the first victim of the anthrax attacks, the 63-year-old south Florida man who had been hospitalized, died. On October 7 investigators announced that evidence of the anthrax bacterium was found in his workplace, the Florida offices of American Media Inc. (AMI), publisher of the National Enquirer, Sun, and other tabloids.

On October 12 New York mayor Rudolph Giuliani announced that an NBC News employee in the office of anchorman Tom Brokaw had tested positive for cutaneous (skin) anthrax, a less dangerous form of the bacterium. Three days later, it was reported that a letter containing suspicious powder was opened in the office of Senator Tom Daschle (South Dakota) in the Hart Senate Office Building in Washington, D.C. The next day the powder tested positive for anthrax.

October 16 brought the news that the infant son of an ABC News producer in New York City had tested positive for exposure to the skin form of anthrax; the baby had visited the ABC News offices weeks earlier, and officials believed exposure had occurred at that time. The same day, it was announced that a second AMI worker, a 73-year-old mailroom employee, was diagnosed with inhalation anthrax and was in intensive care. The announcements brought the number of confirmed anthrax cases to four, two inhalation and two cutaneous. Within days CDC officials had linked all four cases to “the intentional delivery of B. anthracis spores through mailed letters or packages.” The FBI urged the public to handle any suspicious packages with care; to not open, smell, or taste them; and to call 911 immediately.

On October 18 a worker at CBS News in New York was reported to have been infected with skin anthrax. The next day the public learned that an editorial assistant in the Manhattan offices of the New York Post had also been diagnosed with the skin form of the disease. Also on October 18 and 19 the CDC confirmed diagnoses of both inhalation and cutaneous anthrax in New Jersey postal workers, who had begun showing symptoms of infection on October 13.

Between October 19 and 22 four workers from a Washington, D.C., postal facility were confirmed to have been infected with inhalation anthrax and were hospitalized. On October 22 two of them died. Two days later the U.S. postmaster general announced to the public, “There are no guarantees that the mail is safe,” and he advised hand-washing after handling the mail. On October 31 a New York hospital worker died of inhalation anthrax, becoming the fourth fatality. But investigators could not determine how the woman had been exposed to the bacterium.

By mid-November traces of anthrax had been discovered in mail facilities that supplied the CIA, the Senate and House office buildings, the Supreme Court, Walter Reed Army Institute of Research, the White House, Washington, D.C.’s Brentwood Mail Processing and Distribution Center, Washington, D.C.’s Southwest Postal Station, a Kansas City postal facility, the Pentagon’s post office, and four more New Jersey postal facilities. Antibiotics were distributed to thousands of workers as a preventive measure.

On November 16 an anthrax-laced letter addressed to Senator Patrick Leahy (Vermont) was discovered in a batch of quarantined Capitol Hill mail. The handwriting, all uppercase, was similar to that in the letter addressed to Senator Daschle, and the two letters carried identical messages: “09–11–01 / you can not stop us. / we have the anthrax. / you die now. / are you afraid? / death to America. / death to Israel. / Allah is great.” The letters sent to the senators were postmarked October 9, 2001, in Trenton, New Jersey. The message and handwriting in those letters were also similar to those in letters addressed to the editor of the New York Post and to Tom Brokaw at NBC News, both of which read: “09–11–01 / this is next / take penacilin [sic] now / death to America / death to Israel / Allah is great.” The letters sent to the media outlets were postmarked September 18, 2001, also in Trenton, New Jersey. The “Franklin Park, NJ” return address was identical on all four letters; but it was a nonexistent location. Investigators believed that whoever sent out the deadly missives was familiar with the area.

On November 20 it was confirmed that an elderly Connecticut woman, who had died the day before, had been infected with anthrax. The 94-year-old was believed to have been exposed to a letter that had been cross-contaminated in the mail. All five anthrax deaths were caused by the inhalation form of the bacterium. In total, 22 cases of anthrax were identified between October 4 and November 20; 11 of them were the deadly inhalation form (6 people survived) and 11 were the less serious skin form. In all but two cases (the New York hospital worker and the elderly Connecticut woman), the victims were mail-handlers or were exposed to worksites that had been contaminated by mail.

Investigators concluded that all of the anthrax spores were of the same strain, called Ames, but that the letters contained different grades of the bacterium. By November 9, 2001, the FBI had issued a “behavioral/linguistic assessment” of the offender based on the known anthrax parcels: “The offender is believed to be an adult male who has access to a source of anthrax and possesses the knowledge and expertise to refine it.” The FBI headed a multi-agency effort to identify the perpetrator of the deadly attacks.