Early tests show deadly ricin in Senate mailroom
Army lab investigating white, powdery substance
Police surround the Dirksen Senate Office Building, where a substance that tested positive for ricin was found.
WASHINGTON (CNN) -- Preliminary tests on a white, powdery substance found in the mailroom of Senate Majority Leader Bill Frist indicate the presence of the deadly substance ricin, a Homeland Security official said Monday.
A U.S. Capitol police spokeswoman said the department is investigating the matter but would not comment on the substance found, saying only that preliminary tests were positive for a "hazardous substance."
The substance is to be tested further at the Army research laboratory at Fort Detrick, Maryland.
The Homeland Security official, who spoke on condition of anonymity, said those results could be back as soon as Tuesday.
Authorities said people should stay clear of the south side of the fourth floor of the Dirksen Senate Office building.
The substance was found about 3 p.m., and authorities were contacted.
Capitol police said there was nothing overtly suspicious about the envelope -- except for the powdery substance that fell out. Sgt. Contricia Sellers-Ford said there was nothing threatening or otherwise noteworthy about the letter inside the envelope.
She said the envelope was "clipped," meaning it was run through a machine that irradiates all the mail that comes to Capitol Hill -- standard procedure ever since the 2001 anthrax attacks.
Five people died and 13 others were sickened in four states and the District of Columbia when anthrax-laced letters were sent to two U.S. senators and a number of media outlets.
Two of the dead were postal workers who were infected while processing mail. No one has been arrested in connection with the anthrax case.
Authorities stressed the ricin results were preliminary and that field tests often prove unreliable. They also pointed out that though ricin is an effective weapon against a single person, it is difficult to use against large numbers of people at once.
Ricin is a natural, highly toxic compound that comes from castor beans, used to make castor oil. It can be inhaled, ingested or injected.
There is no known antidote, according to the Centers for Disease Control and Prevention. One milligram of ricin, a dose the size of the head of a pin, can kill an adult.
If inhaled, ricin can cause death in 36 to 48 hours from failure of the respiratory and circulatory systems.
If ingested, it causes nausea, vomiting and bleeding of the stomach and intestines, followed by failure of the liver, spleen and kidneys, and death by collapse of the circulatory system.
Injected ricin immediately kills the muscles and lymph nodes near the site of the injection. Failure of the major organs and death usually follows, the CDC said.
In a notorious Cold War assassination, Bulgarian dissident Georgi Markov, living in London, England, was killed in 1978 by a poison dart filled with ricin and fired from an umbrella.
In October, traces of ricin were discovered inside a small metal container in an envelope at a postal handling facility in Greenville, South Carolina. With the poison was an "angry, unsigned note." (Full story)
Several U.S. agencies are offering a reward of up to $100,000 for information leading to the arrest and conviction of those responsible.
The Dirksen building was one of the buildings affected by the anthrax mailings in 2001. Its offices were closed for days while authorities cleaned its mailroom.