Topic: Ricin

(AP/Seth Wenig)

Darlene Superville, Colleen Long
(AP/Carolyn Kaster)

Associated Press
(AP/Seth Wenig)

Associated Press
U.S. Marines dressed in protective suits prepare to enter the closed Russell Senate Office Building on Capitol Hill, to retrieve mail that could be contaminated, Feb. 4, 2004. (Reuters)

Holbrook Mohr
(Reuters/Jason Reed)

Salon Staff
A Prince George's County, Md. firefighter dressed in a protective suit walks into a government mail screening facility in Hyattsville, Md., Wednesday, April 17, 2013. (AP/Alex Brandon)

Holbrook Mohr
A Prince George's County, Md. firefighter dressed in a protective suit walks into a government mail screening facility in Hyattsville, Md., Wednesday, April 17, 2013. (AP/Alex Brandon)

Jeff Amy, Emily Wagner Pettus
U.S. Marines dressed in protective suits prepare to enter the closed Russell Senate Office Building on Capitol Hill, to retrieve mail that could be contaminated, Feb. 4, 2004. (Reuters)

Associated Press
A Prince George's County, Md. firefighter dressed in a protective suit walks into a government mail screening facility in Hyattsville, Md., Wednesday, April 17, 2013. (AP/Alex Brandon)

Associated Press
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Jesse Washington
Salon logo

Holbrook Mohr, Adrian Sainz
U.S. Sen. Roger Wicker, R-Miss. (AP/Rogelio V. Solis)

Associated Press
A Prince George's County, Md. firefighter dressed in a protective suit walks into a government mail screening facility in Hyattsville, Md., Wednesday, April 17, 2013. (AP/Alex Brandon)

Holbrook Mohr
U.S. Marines dressed in protective suits prepare to enter the closed Russell Senate Office Building on Capitol Hill, to retrieve mail that could be contaminated, Feb. 4, 2004. (Reuters)

Ricin: A long, lethal history

Alex Seitz-Wald
Castor oil plant (Wikipedia)

Why ricin is so scary

Andrew Leonard
U.S. Sen. Roger Wicker, R-Miss. (AP/Rogelio V. Solis)

Jacob Sugarman, Alex Halperin