(Washington, DC)  --  White House spokesman Jay Carney confirms a letter to President Obama, containing a suspected toxic substance, was intercepted and quarantined.  Carney said the President has been briefed about the letter.  The letter was intercepted at an off-site postal facility.  At least two letters to lawmakers, possibly containing the poison ricin [[ RYE-sin ]], were also intercepted and quarantined this week.  Authorities think the suspected toxin on the letter to the President is also ricin.  

Police and security officials are on high-alert after this week's deadly terrorist bombings in Boston.  Echoing remarks by the President, Carney said investigators are resolved to find who did it and why and to bring the perpetrator or perpetrators to justice.  He noted that it's still unknown whether the bombing plot originated in the U.S. or abroad.  Carney said the President has full confidence in federal investigators.  The Boston probe is being led by the FBI, which is also in charge of the letters probe.