Paul Kevin Curtis, the Mississippi man accused of mailing ricin-positive letters to the president—and other national leaders—has been formally charged, the U.S. Department of Justice said Thursday. The 45-year-old part-time Elvis impersonator sent the poison-filled letters in hopes of exposing what he believed to be a conspiracy to sell human body parts on the black market. Curtis's letters, intended for President Obama and Sen. Roger Wicker (R-Mississippi), were intercepted before arrival. Officials confirmed Thursday that both letters had tested positive for ricin. “To see a wrong and not expose it, is to become a silent partner to its continuance," Curtis wrote.