Investigation and Interception
The Federal Bureau of Investigation (FBI) and the U.S. Postal Inspection Service confirmed they are working together to identify those responsible for the mailings. According to the FBI, "Some of the letters contained an unknown substance and we are working closely with our law enforcement partners to respond to each incident."
The Senate Sergeant at Arms notified congressional staff that law enforcement officials are working to intercept additional letters before they are delivered, though some may still reach their intended destinations. Federal authorities have urged recipients to treat the mail as "potentially hazardous."
Brendan Donahue, a senior official with the U.S. Postal Inspection Service, addressed the investigation during a press conference. "We are committed to protecting our nation’s election officials from threatening and dangerous mail. Any threat or attack on an election official is unacceptable," Donahue said.