Federal authorities are investigating a troubling series of letters containing suspicious substances that were mailed to addresses across the country. The reported recipients included congressional offices on Capitol Hill, Secretary of State offices, and election offices connected to them.

Reports described the material as suspicious powder, while the FBI identified it as an unknown substance. The FBI said some of the letters had been sent nationwide and that multiple law enforcement agencies were responding.

The FBI said: “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.”

The bureau also said: “We are also working with our partners to identify the individual or individuals responsible for the letters. The FBI will continue to safeguard the public and secure elections for American citizens.”

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

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The FBI, U.S. Postal Inspection Service, and Capitol Police are involved in the investigation. Their work includes responding to the suspicious mailings and attempting to determine who was responsible for sending them.

A Senate email warned that authorities were trying to prevent more of the letters from reaching their intended recipients. The message acknowledged, however, that law enforcement might not intercept every envelope before delivery.

According to the email, law enforcement officials were “working to intercept any additional letters before they are delivered; however, it is possible that some letters may reach their destinations.”

The Ohio Secretary of State was among the intended recipients. That letter did not reach the office because it was stopped by the U.S. Postal Service.

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Election officials responded by condemning threats against the people responsible for administering elections. The National Association of Secretaries of State and the National Association of State Election Directors issued a joint statement addressing the mailings.

“As we have each stated in the past, threats against election officials and workers have no place in our democracy. Those who administer our elections should never fear for their safety while carrying out their essential duties,” the organizations said.

The groups also emphasized the security work taking place around election offices and employees. “Election officials take these matters seriously and work closely with law enforcement and security partners to protect their personnel and facilities,” their statement added.

Ohio Secretary of State Frank LaRose addressed the incident Wednesday and echoed the organizations’ concerns. He said election officials should “never have to fear for their personal safety while performing their duties.”

LaRose also said his office was working with state and federal law enforcement following the mailing directed at it. His office was therefore among the state election operations coordinating with authorities after becoming an intended recipient.

@BillMelugin_ @lookner Oklahoma got one https://t.co/ZzKVQ3iAtb

— P (@P71714147) October 15, 2026

The NY Post reported that one of the suspicious envelopes carried a return address. A warning sent to Capitol Hill staff reportedly included a photograph of an envelope bearing that address and a postmark reading “DSA.”

The return address pointed to a Financial District building that the Democratic Socialists of America had previously listed on its membership forms. The Democratic Socialists of America responded by saying the organization was no longer located at that address.

FBI and Capitol Police investigating suspicious letters sent to Congress with return address linked to Democratic Socialists of America.

-Letters containing suspicious substances were mailed to congressional offices. -Envelopes were marked “DSA” and listed a return address previously used on Democratic Socialists of America membership forms. -Some letters were intercepted at locations outside Congress. -Senate staff have been warned that additional letters could still arrive. The FBI, Capitol Police, and U.S. Postal Inspection Service are investigating. Are DSA communists now threatening members of Congress? — Benny Johnson (@bennyjohnson) October 15, 2026

Emails sent to Capitol Hill staff Thursday said the FBI, U.S. Postal Inspection Service, and Capitol Police were investigating letters “containing suspicious substances” that had been mailed to congressional offices. The warning placed Hill personnel on notice as authorities continued working to intercept additional mailings.

The investigation remains focused on responding to each incident and identifying the individual or individuals responsible. Authorities are also coordinating across agencies as suspicious letters directed at political and election offices continue to draw scrutiny.

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