On this day, July 29, in 2008, Bruce Ivins, an Army microbiologist suspected of mailing letters laced with anthrax across the country, committed suicide. The anthrax attacks, which began shortly after the September 2001 terrorist attacks, killed five people and infected 17. The Federal Bureau of Investigation called the ensuing search “one of the largest and most complex in the history of law enforcement.”

The investigation focused on Ivins, who had once worked to develop an anthrax vaccine for the military. He worked closely with the substance and had created a batch that matched samples from the letters.