2001 Anthrax Attacks

Weeks following the 9/11 attacks, several news outlets and senators in the USA received letters laced with anthrax spores. Five people were killed and 17 were injured. According to the FBI, the ensuing investigation became “one of the largest and most complex in the history of law enforcement.” The prime suspect in the case was a scientist named Bruce Edwards Ivins who worked in U.S. government's biodefense labs. He committed suicide with an overdose of acetaminophen in 2008. So the case still remains open.