Ricin attackMississippi man arrested for sending ricin letters to Obama, Sen. Wicker

The FBI confirmed yesterday (Wednesday) that a letter addressed to President Obama was found to contain the toxin ricin. As is the case with all the mail sent to the White House, the letter was screened in a remote mail sorting facility in Anacostia, a neighborhood in southeast Washington, D.C., and intercepted. The facility is run by the Secret Service and employs about fifty screeners.

The FBI arrested a man from Tupelo, Mississippi, on suspicion that he was behind the ricin letters to the White House and to Senator Roger Wicker (R-Mississippi), who lives in Tupelo.

The FBI said in a statement that a letter intercepted in the sorting facility contained “a granular substance that preliminarily tested positive for ricin.” The agency said there was “no indication” of any connection to the bombings Monday that killed three spectators at the Boston Marathon.

The Washington Post reports that the police and the FBI were also investigating suspicious packages in and near the offices of several members of Congress.

The letter containing the suspicious substance was sent to a military installation in Maryland where preliminary testing found indications of ricin.

CNN reported that the letters to Obama and Wicker were similar in the language they used and signatures. Each of the letters read: “To see a wrong and not expose it, is to become a silent partner in its continuance.” CNN said the letters were signed: “I am KC and I approve this message.”

On the Hill, the U.S. Capitol Police was investigating suspicious packages delivered to the front office of Senator Richard C. Shelby (R-Alabama) in the Russell Senate Office Building, and also a package left in the atrium of the Hart Senate Office Building.

Jonathan Graffeo, a spokesman for Shelby, said in a statement: “The Capitol Police have given us the all clear. Sen. Shelby and staff are unharmed. Questions relating to any details of the investigation should be referred to the Capitol Police.”

When the letter to the Wicker was detected, the Capitol Police ordered the evacuation of all first-floor offices in the Hart Senate Office Building. Staffers occupying offices located on higher floors were told to stay in their offices.

Senator Carl Levin (D-Michigan) said in a statement that a staffer received “a suspicious-looking letter” Wednesday morning at the senator’s office in Saginaw, Michigan.

“The letter was not opened, and the staffer followed the proper protocols for the situation, including alerting the authorities, who are now investigating,” Levin said. “We do not know yet if the mail presented a threat.”

The Post reports that in late morning Wednesday, an envelope was hand-delivered to the third-floor Hart office of Senator Joe Manchin (D-West Virginia), and Capitol Police removed the letter for testing.

In Phoenix, a suspicious letter was discovered Wednesday at the office of Senator Jeff Flake (R-Arizona), according to spokeswoman Genevieve Rozansky.

“There was a suspicious letter intercepted by a member of Senator Flake’s staff at his Phoenix office,” she said in an e-mailed statement. “Law enforcement officials are on the scene, and all staff members are safe. We will release details as we know more.”

The White House receives more than 10,000 letters a week. Since Obama became president in 2009, the Secret Service has intercepted at least half dozen letters that went beyond threatening words – some of these letters contained suspicious powder or HIV-positive blood.

The Post notes that in 2004, three Senate office buildings were closed after preliminary tests of suspicious substance in a letter delivered to the office of the Senate majority leader found the substance to be ricin.

The AP reported that subsequent tests found that the preliminary test may have picked up non-toxic byproducts of the castor bean plant used in paper production.