A letter addressed to Barack Obama has been found to contain a lethal toxin, the FBI revealed.
The letter sent to the US President is related to the package intended for a US senator, the FBI have confirmed. Mississippi Senator Roger Wicker was sent a letter with traces of the deadly poison ricin but it was intercepted by authorities.
Both letters were postmarked from Memphis, Tennessee, dated April 8 and say: "To see a wrong and not expose it, is to become a silent partner to its continuance." Both are signed, "I am KC and I approve this message."
The FBI says preliminary tests on the letter sent to Obama indicate the presence of the poisonous substance ricin. The letter is undergoing further testing because preliminary field tests can be unreliable, creating false positives.
All mail has been sorted and tested off-site since letters laced with anthrax were posted to two senators in 2001.
The FBI says there is no indication of a connection to the Boston Marathon bombing on Monday.
“This facility routinely identifies letters or parcels that require secondary screening or scientific testing before delivery,” Secret Service spokesman Edwin Donovan said in a statement.
“The Secret Service is working closely with the US Capitol Police and the FBI in this investigation,” he added.
Michigan Senator Carl Levin also revealed that his regional office in his state received a suspicious letter and that authorities have been alerted. US authorities are now investigating.
The news comes the day after it emerged that a letter laced with the deadly poison ricin has been sent to Mississippi Senator Roger Wicker.
The FBI launched an immediate investigation into the letter and sent it for further analysis after preliminary tests revealed traces of ricin - a poison that can cause death within 72 hours when exposed to as little as a pinhead amount.
It was intercepted in a mail handling facility en route to Senator Wicker and immediately quarantined.
Terrance Gainer, the Senate sergeant at arms, said in a statement: “Senate employees should be vigilant in their mail handling processes for ALL mailings,“ Gainer said in his written statement.”
Members of the Senate were briefed on the incident by Gainer during a meeting with FBI Director Robert Mueller and Janet Napolitano, the secretary of Homeland Security, yesterday on the bombings in Boston.
Several senators told reporters after the briefing that the incident reminded them of the anthrax attacks in the wake of the September 11, 2001, attacks on the Pentagon and World Trade Center.
The ricin test came one day after the explosions at the Boston Marathon that killed three people and injured 176.
“I don't know if it's a coincidence. It's too early to tell. We don't know enough about Boston,” said Senator Richard Durbin, the No. 2 Democrat in the Senate.
All mail to the US Senate had been stopped, and post offices at the Capitol had been closed as a precaution, the senators said. They were getting in touch with their state offices, where mail is not subject to the same extensive screening, to ensure that precautions were being put in place.
Many senators expressed concern about their staffs and the risks to postal workers.
A law enforcement source, speaking on condition of anonymity, said initial field tests on the letter produced mixed results, prompting authorities to order further analysis at an accredited laboratory.
It was not immediately clear whether Wicker, a Republican, had attended the briefing by Mueller and Napolitano that was open to all senators from both parties.
Wicker issued a statement saying only that the matter was being investigated and expressing gratitude for thoughts and prayers on his behalf.
“This matter is part of an ongoing investigation by the United States Capitol Police and FBI. I want to thank our law enforcement officials for their hard work and diligence in keeping those of us who work in the Capitol complex safe,” he said in the statement.
Wicker, a former member of the House of Representatives, has been a member of the Senate since he was first appointed to a vacant seat in December 2007. He won a special election to serve the remainder of that term, and was re-elected in November 2012 to a full six-year term.
Several senators noted that the system of mail screening, begun after the anthrax attacks, had worked.
“The bottom line is the process we have in place worked,” said Claire McCaskill, a Democratic senator from Missouri. She said a suspect had been identified, and said it was someone who wrote to senators often.
Other officials could not immediately confirm that report.
There was another ricin scare at the US capital in 2004, when tests identified a letter in a Senate mail room that served the office of Bill Frist, a Tennessee Republican who was then the Senate Majority Leader.
The most famous case of ricin poisoning was in 1978 when dissident Bulgarian writer Georgi Markov was killed after a passerby in London jabbed him with an umbrella that injected a tiny ricin-filled pellet.
In 2001, the Capitol was one target in a series of anthrax attacks that killed at least five people on the East Coast, including two Washington postal workers.
Letters containing anthrax spores were mailed to the Washington offices of two senators and to news media outlets in New York and Florida.