Paul Kevin Curtis has been charged with making threats against the president and sending threatening letters, the Justice Department said Thursday.
Curtis was arrested by the FBI on Wednesday at his home in Corinth, Mississippi, on suspicion of sending ricin-laden letters to President Barack Obama and Sen. Roger Wicker of Mississippi.
Further test results were expected later Thursday on the contents of the envelopes.
The letters to Wicker and Obama were stopped at a government mail screening facility after initial tests indicated the presence of ricin.
Because initial tests can be "inconsistent," the envelopes were sent off for additional tests, an FBI statement said.
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