A Texas woman who had a series of small roles in television shows including AMC’s “The Walking Dead” pleaded guilty in a case in which she was accused of sending letters tainted with the poison ricin to President Barack Obama and New York Mayor Michael Bloomberg, according to The Hollywood Reporter.

Shannon Guess Richardson’s plea is part of a deal that her lawyer, Tonda Curry, has said will limit her prison time to 18 years, the story reports. Prosecutors, however, say she faces life in prison for the charge to which she entered the guilty plea, THR reports.

At a federal court in Texarkana the actress pleaded guilty to a federal charge of possessing and producing a biological toxin. She was arrested earlier this year after officials said she had attempted to frame her estranged husband, Nathan Richardson, for the letters, the story adds.

"Prosecutors say Shannon Richardson mailed three letters from New Boston, outside Texarkana, then went to police and claimed that her husband had done it," THR reports. "She acknowledged in a signed plea agreement document filed Tuesday that she ordered castor beans online and learned how to process them into a substance used to make ricin. She obtained an email address, a PayPal shopping account and a post office box in her husband’s name without his knowledge, according to the document."

Richardson admits in the document that on the morning of May 20, she waited for her husband to go to work, and says: "After he left the house, I printed the mailing labels for President Barack Obama, New York City Mayor Michael Bloomberg, and Mark Glaze with The Raben Group." All of the targets appear to be chosen for their pro-gun control efforts.

"Glaze is director of Mayors Against Illegal Guns, Bloomberg’s group advocating for tougher gun control," THR notes.

The plea document says the letter to Obama read: "What’s in this letter is nothing compared to what ive got in store for you mr president."

It reportedly continues: "You will have to kill me and my family before you get my guns. Anyone wants to come to my house will get shot in the face."

Shannon Richardson reportedly admits mailing the letters, then attempting to blame Nathan Richardson and lying to authorities.

The THR report adds: "Curry has said that Richardson wanted to ‘tell the government who else was involved in those offenses,’ but declined to name anyone. In the document filed Tuesday, known as a factual resume, Richardson does not name anyone else but says that the supplies she ordered ‘were used to make ricin’– not that she made the ricin herself."

Shannon Richardson, 35, has reportedly also appeared on the TV shows “The Vampire Diaries” and "Franklin & Bash," among others, and in the feature films "The Change-Up" and “The Blind Side.”

Shannon Guess Richardson