Shannon Guess Richardson pleads guilty in ricin letters case

Shannon Guess Richardson pleaded guilty in federal court on Tuesday to making the biological agent ricin that was sent in letters to President Barack Obama and New York Mayor Michael Bloomberg.

As part of a deal reached with federal prosecutors that has yet to be approved by a judge, Shannon Guess Richardson, 36, would spend 18 years in prison and then five years on supervised release, according to court documents.

Shannon Guess Richardson, whose career included minor television roles in shows such as The Walking Dead, pleaded guilty to charges of manufacturing and possessing the toxic agent ricin, which was found in the letters.

She was initially charged with one count of making a threat against the President of the United States and two counts of mailing threatening communications.

Shannon Guess Richardson tried to blame her husband for the letters, sent in May, testing positive for the presence of ricin, according to prosecutors.