Federal agents are actively investigating a series of letters sent to congressional offices that contain suspicious substances. The FBI, U.S. Capitol Police, and Postal Inspection Service launched this probe after receiving reports on Thursday. Additional letters are being intercepted by law enforcement before delivery, though some might still arrive at their destinations.
Senior Capitol Hill staff received a warning notice detailing the threat to various addresses nationwide. According to ABC News, the investigation covers multiple letters containing suspicious substances mailed to different locations. The notice included a photo of one envelope postmarked “DSA” with a return address tied to the Democratic Socialists of America. Fox News stated that it is not yet known if the DSA participated in mailing these letters.
Today, the Executive Tower was evacuated after a Hazardous Materials Incident. I’m glad that there are no reported injuries at this time and thankful to the first responders for their swift action.
Threats against our hard-working public servants are unacceptable. Anybody responsible for threatening or intimidating elections officials should be held accountable to the fullest extent of the law.
— Governor Katie Hobbs (@GovernorHobbs) October 16, 2026
Two Democratic senators received direct notifications about the mailings sent to their respective offices. According to reports, a spokesperson for Sen. Chris Murphy, the senator’s office received a letter containing a suspicious substance. He stated that FBI, SAA, and Capitol Police promptly notified his office of the letter, and collaboration with them and federal law enforcement continues.
BREAKING: FBI confirms to @FoxNews they’re investigating suspicious letters that were sent out nationwide with unknown substances in them, including to some offices on Capitol Hill.
FBI spox:
“The FBI and U.S. Postal Inspection Service are investigating a series of suspicious mailings sent to various addresses nationwide, including Secretary of State offices and their related election offices. Some of the letters contained an unknown substance and we are working closely with our law enforcement partners to respond to each incident. We are also working with our partners to identify the individual or individuals responsible for the letters. This FBI will continue to safeguard the public and secure elections for American citizens.”
— Bill Melugin (@BillMelugin_) October 15, 2026
Officials stated that safety protocols prevented immediate harm to the staff members. Sorbe remarked that thanks to these actions and safety measures, the Senator and staff faced no immediate threat. A spokesperson for Sen. Alex Padilla confirmed similar actions. They reported receiving FBI notification that a letter with a suspicious substance was mailed to one office but stopped by USPS.
Ohio Secretary of State says his office was an intended recipient:
https://t.co/xEzNP3hyKh
— Bill Melugin (@BillMelugin_) October 15, 2026
The probe extends beyond Congress to include Secretary of State offices and related election offices across the country. RedState indicated that the FBI and Postal Inspection Service are probing a string of suspicious mailings directed at these critical election centers. An official mentioned that certain letters held an unknown substance while they coordinate with law enforcement partners to address every incident.
Authorities have not publicly identified the specific nature of the unknown substances found inside the envelopes. The New York Post noted that the warning advised all staff to treat any suspicious items as potentially hazardous. Agents from the federal government are also seeking to pinpoint the person or people behind the letters.
NEW: The FBI, US Postal Inspection Service and Capitol Police are investigating letters “containing suspicious substances” that were mailed to congressional offices, according to an email sent to Hill staff Thursday
One of the letters is postmarked “DSA” with a return address in the same building where the Democratic Socialists of America has been headquartered
— Josh Christenson (@jchristenson_) October 15, 2026
This situation places a heavy burden on local postal workers and government staff who must remain vigilant. The New York Post verified that some of these missives were also stopped at locations besides congressional offices.
