https://insiderwire.com/news/f-b-i-investigating-letters-with-unknown-substance-sent-to-election-offices Insider Wire en 2026-10-15T18:23:24.983Z F.B.I. Investigating Letters With Unknown Substance Sent to Election Offices bioterrorism threat, election security, fbi, law enforcement, midterm elections, secretaries of state, suspicious mail, u.s. news https://insiderwire.com/og/media/1792088551254-cover-1792088551104-uzVYkz2Lgxa7nsse7E5toxkGmJpM41.webp.jpg?v=4 F.B.I. Investigating Letters With Unknown Substance Sent to Election Offices 2026-10-15T18:23:24.983Z