Washington, Apr 17 (EFE).- The FBI on Wednesday ruled out that letters containing a substance suspected of being the poison ricin sent to U.S. President Barack Obama and a senator are linked to the bombings at the Boston Marathon.
"The investigation into these letters remains ongoing, and more letters may still be received. There is no indication of a connection to the attack in Boston," the FBI said in a statement.
The letter containing a granulated substance that tested positive as ricin was intercepted in an off-site mail screening facility before being delivered to the White House, the FBI said.
The envelope addressed to the president was immediately quarantined by the Secret Service and an investigation was launched in cooperation with the FBI.
Obama was informed of the letters directed to him and to Mississippi Republican Sen. Roger Wicker, White House spokesman Jay Carney told reporters.
The FBI also said that screening procedures at a second mail inspection facility on Wednesday morning detected ricin in another letter addressed to the White House, and all the mail at those two installations is now being subjected to a series of tests.
"Only a full analysis performed at an accredited laboratory can determine the presence of a biological agent such as ricin. Those tests are currently being conducted and generally take 24 to 48 hours," the FBI said.
U.S. Capitol Police on Wednesday closed parts of the Senate's Russell and Hart office buildings after receiving reports of two suspicious packages, and they are questioning the person who delivered the packages to the reception desks of those buildings.