12/10/2013 08:23 EST | Updated 02/09/2014 05:59 EST

Ricin Letters: Shannon Guess Richardson Expected To Plead Guilty To Sending Letters To Obama

DALLAS - A Texas woman is expected to plead guilty to sending ricin-laced letters to President Barack Obama and New York Mayor Mike Bloomberg.

Shannon Guess Richardson has a federal court appearance scheduled Tuesday in Texarkana, Texas. She's expected to plead guilty under a deal that caps any prison sentence at 18 years.

Her attorney, Tonda Curry, said Richardson was ready to admit her role in sending toxic letters to Obama, Bloomberg and the head of Bloomberg's pro-gun control group.

Prosecutors say that before her arrest in June, Richardson tried to frame her now-estranged husband for mailing the letters containing ricin, a powdery substance that can cause respiratory failure if inhaled.

Richardson has had minor roles in the television series "The Walking Dead" and the movie "The Blind Side."

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