The FBI, U.S. Postal Inspection Service, and U.S. Capitol Police are investigating more than 100 such letters, some of which contain threats of a civil war and return addresses linked to the Democratic Socialists of America. Although Sergeant at Arms William McFarland announced on Oct. 19 that none of the letters delivered to congressional offices have been determined to contain hazardous substances, officials have warned that more suspicious mail may still reach destinations. The series of events coincided with the 25th anniversary of the anthrax attacks on Capitol Hill.
