Investigating the post-9/11 bioterror attacks that had people afraid to open their mail: The 2001 Anthrax Attacks. Weeks after September 11th, letters laced with a mysterious powder began arriving at newsrooms and Senate offices. The powder was quickly identified as anthrax and in just days, five people died and 17 others were left ill. The investigation spiraled into one of the most complex and controversial in FBI history. Today, we examine the infamous 2001 Anthrax Attacks. Sensitive topics: suicide, bioterrorism, terrorism, political themes