Everett Dutschke, right, talks with a federal agent near the site of a martial arts studio he once operated in Tupelo Wednesday. Dutschke faces federal charges accusing him of sending ricin-laced letters to President Obama and others. Rogelio V. Solis/AP hide caption

itoggle caption Rogelio V. Solis/AP

A screen image from a video on the YouTube channel where Paul Kevin Curtis has posted clips of his performances — in this case, as "Elvis." YouTube.com hide caption

itoggle caption YouTube.com

The bean of the castor-oil plant, Ricinus communis, is used in the production of castor vegetable oil and ricin, a poison. Sasha Vasko/via Flickr hide caption

itoggle caption Sasha Vasko/via Flickr