FBI agents arrested Shannon Elizabeth Guess Richardson (pictured) this morning in connection with the ricin-tainted letters sent to the White House and the offices of Michael Bloomberg and Mayors Against Illegal Guns. According to NPR (yes, that NPR) her husband and original person of interest Nathan Richardson has been cleared of suspicion. The FBI now believes that Shannon sent the poison letters as part of a plot to frame her husband and divorce him, and that the letters’ rants about gun control were a red herring.