FBI probes suspicious mailings to congressional offices with DSA return address

The Federal Bureau of Investigation and the U.S. Postal Inspection Service are examining a series of suspicious mailings sent to various addresses nationwide, including multiple congressional offices and Secretary of State offices. A notice from the U.S. Senate Sergeant at Arms warned senior Capitol Hill staff that multiple letters containing suspicious substances were mailed out on Thursday, prompting a coordinated law enforcement response.

An email notice obtained by Fox News Digital, first reported by Punchbowl News, was sent to chiefs of staff, administrative managers, and state directors. The alert stated that law enforcement officials are working to intercept additional letters before delivery, though it acknowledged that some letters may have already reached their destinations. The notice instructed that all suspicious letters, packages, or substances be treated as potentially hazardous.

An image included in the Sergeant at Arms' notice showed one envelope bearing a return address in the top-left corner for the headquarters of the Democratic Socialists of America in New York City. It remains unclear whether the DSA had any involvement in sending the letters. Fox News Digital reached out to the organization for comment but has not received a response.

An FBI spokesperson confirmed in a statement that the agency and the Postal Inspection Service are investigating the incident. The spokesperson noted that some of the letters contained an unknown substance and that investigators are working closely with law enforcement partners to respond to each incident. The statement added that officials are working to identify the individual or individuals responsible for the letters, emphasizing a commitment to safeguarding the public and securing elections.

The investigation comes on the 25th anniversary of an anthrax-laced letter opened by a staffer in the office of then-Senate Majority Leader Tom Daschle on October 15, 2001.