Law enforcement confirms ricin letter sent to Sen. Wicker

Law enforcement officials confirmed on Tuesday that they had launched an investigation into an envelope containing the poison ricin that was sent to Sen. Roger Wicker (R-Miss.).

"The U.S. Capitol Police, the FBI and other agencies are involved in the investigation of this mailing," Senate Sergeant-at-Arms Terrance Gainer said, GovExec.com reports.

Lawmakers were briefed on the letter behind closed doors as they were being briefed on the Boston bombings but said that no indication was given that the two events were connected.

The ricin-filled envelope was intercepted at the Senate Mail Handling Facility before it reached Capitol Hill. The envelope tested positive for ricin in an initial screening, which was again confirmed by subsequent testing.

Gainer said that envelope was not "outwardly suspicious." The letter was postmarked form Memphis, Tenn., with no return address, according to GovExec.com.

The letter echoes the weeks that followed the Sept. 11, 2001, anthrax letter attacks that killed five people and sickened an additional 17. Those letters were sent to Capitol Hill offices and media outlets.

"This matter is part of an ongoing investigation by the United States Capitol Police and FBI," Wicker said. "I want to thank our law enforcement officials for their hard work and diligence in keeping those of us who work in the Capitol complex safe. Gayle and I appreciate everyone's thoughts and prayers."