WASHINGTON -- The FBI says the letters sent to President Barack Obama and Sen. Roger Wicker are related and are both postmarked out of Memphis, Tenn., dated April 8.
In an intelligence bulletin obtained by The Associated Press, the FBI says the letters both say: "To see a wrong and not expose it, is to become a silent partner to its continuance." Both letters are signed, "I am KC and I approve this message."
The FBI says the substance in both letters have preliminarily tested positive for ricin, a potentially fatal poison. The letter is undergoing further testing because preliminary field tests can be unreliable, creating false positives.
The letter was intercepted at a facility away from the White House. It comes the day after officials said a letter sent to Sen. Roger Wicker tested positive for poisonous ricin. That letter to Wicker, a Republican, was intercepted at a Senate mail facility just outside Washington.
The FBI says there is no indication of a connection to the bombing at Monday's Boston Marathon.