A U.S. Navy veteran has been arrested for allegedly sending threatening letters addressed to the Pentagon and the White House, some of which were initially feared to have contained the deadly poison ricin. Subsequent tests determined the mailings contained a castor-bean substance, an ingredient which is used to manufacture ricin. William Clyde Allen III was taken into custody in Utah on Wednesday, two days after the letters were discovered. Federal charges were expected to be filed Friday. Allen served in the Navy for four years, leaving the service in 2002. His motive is unclear. The threatening letters were addressed to Secretary of Defense James Mattis and Chief of Naval Operations John Richardson.
