Senate Majority Leader Harry M. Reid (D-Nev.) and other senators exiting an FBI briefing on the Boston attacks, told reporters that the letter was tested at the facility and came up positive for ricin. The letter was postmarked Memphis, Tenn., and had no suspicious markings or return address, according to a message sent to congressional staffers by Senate Sergeant at Arms Terrance Gainer. Sen. Claire McCaskill told reporters after a briefing for lawmakers that a suspect has already been identified in the incident, but a knowledgeable source said no one was in custody Tuesday night. McCaskill said state offices have been told what to look for if there are more letters containing the toxic substance. included a substance that has tested positive for the toxic substance ricin. Officials gave no indication why the letter was sent to Wicker, a low-profile senator in his second term. The U.S. Senate mail facility is currently closed for more testing — all mail bound for Capitol Hill is now being directed through a U.S. House facility.
– Scary story breaking out of DC: A letter addressed to Republican Mississippi Sen. Roger Wicker tested positive for the poison ricin, reports Politico. The envelope never got to him, reports CNN, which says it was intercepted at an off-site facility that sorts mail for the Capitol. Three separate tests turned up positive for the highly toxic poison. Authorities have identified a suspect, said Sen. Claire McCaskill, adding only that it was someone who writes lots of letters to lawmakers. It's not clear why the apparent target was Wicker, described by the Washington Post as a "low-profile senator in his second term." (He replaced Trent Lott in 2008.) The envelope got detected at a facility set up in 2001 after some senators were sent letters tainted with anthrax. "The bottom line is, the process we have in place worked," said McCaskill. FBI chief Robert Mueller and Homeland Security chief Janet Napolitano briefed senators today, though it's not clear when the letter was received.