FBI agents have arrested a Denver man accused of sending intimidating letters containing a non-poisonous white powder to several government offices, including those of U.S. Senators Mark Udall and Michael Bennet and the offices of U.S. Representatives Mike Coffman and Diana DeGette. 9News  reports that Jay DeVaughn, a reportedly exemplary college librarian, so far faces a federal charge of mailing threatening communications. DeVaughn has been the director of library services at the Community College of Aurora, according to The Denver Post , and "was clean" after a background check before he got the job two-and-a-half years ago, says the college president. An affidavit notes that FBI agents believe DeVaughn put four suspicious letters into a drive-through drop box at the Wellshire Post Office at 2080 S. Holly St. on February 22 (via 7News ). Those letters were addressed to an Argentine Embassy and included plastic sandwich bags containing a "white powdery substance and a single sheet of paper," according to the arrest affidavit. The paper contained more than 200 black-and-white photos of men and women. "Por los Desparecidos" [sic]---roughly, "For those who have disappeared"---was written at the bottom of the paper. DeVaughn, agents say, could perhaps be linked to other recent white powder incidents.