A 2006 post on a blog for Baker's office says the comment originally was a criticism of insurance companies. Since then, the site says, it "has been a quote that has been picked up and quoted (sometimes without attribution) around the net" and "people are using it about all kinds of injustices."
The letter sent to Wicker had a Memphis, Tennessee, postmark and no return address, Senate Sergeant-at-Arms Terrance Gainer wrote in an e-mail to senators and aides Tuesday. Wicker has been assigned a protective detail, according to a law enforcement source.
A laboratory in Maryland confirmed the presence of ricin on the letter addressed to Wicker after initial field tests also indicated the poison was present, according to Gainer. However, the FBI said additional testing was needed because field and preliminary tests produce inconsistent results.
"Only a full analysis performed at an accredited laboratory can determine the presence of a biological agent such as ricin," according to the bureau.
A law enforcement source said further tests would be conducted at the Army's biomedical research laboratory at Fort Detrick, Maryland.
After the arrest was announced Wednesday night, Wicker released a statement thanking "the men and women of the FBI and U.S. Capitol Police for their professionalism and decisive action in keeping our family and staff safe from harm." His offices in Mississippi and Washington "remain open for business to all Mississippians," Wicker said in the statement.
Mail for members of Congress and the White House has been handled at offsite postal facilities since the 2001 anthrax attacks, which targeted Sen. Patrick Leahy, D-Vermont, and then-Majority Leader Tom Daschle, D-South Dakota.
Senate mail service shut down
Senators were told Tuesday that the mail facility would be temporarily shut down "to make sure they get everything squared away," Sen. Claire McCaskill, D-Missouri, said Tuesday afternoon.
"The bottom line is, the process we have in place worked," she said.
Senate Minority Leader Mitch McConnell, R-Kentucky, also praised the postal workers and law enforcement officers for "preventing this threat before it even reached the Capitol."
"They proved that the proactive measures we put in place do, in fact, work," he said.
Ricin is a highly toxic substance derived from castor beans. As little as 500 micrograms -- an amount the size of the head of a pin -- can kill an adult. There is no specific test for exposure and no antidote once exposed.
It can be produced easily and cheaply, and authorities in several countries have investigated links between suspect extremists and ricin. But experts say it is more effective on individuals than as a weapon of mass destruction.
Ricin was used in the 1978 assassination of Bulgarian dissident Georgi Markov. The author, who had defected nine years earlier, was jabbed by the tip of an umbrella while waiting for a bus in London and died four days later.
A previous ricin scare hit the Capitol in 2004, when tests identified it in a letter in a Senate mail room that served then-Majority Leader Bill Frist's office. The discovery forced 16 employees to go through decontamination procedures, but no one reported any ill effects afterward, Frist said.