Under the deal, Shannon Guess Richardson would plead guilty to a federal charge of possessing and producing a biological toxin, her attorney, Tonda Curry, said. Final details of what Richardson will admit are still being worked out, but 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.
"Shannon is anxious to admit her role in ordering the components to make the ricin, her role in the letters that contained the ricin, and to tell the government who else was involved in those offenses," Curry said.
Curry did not say more about Richardson's possible motives or whom she might name.
A plea hearing is scheduled for Dec. 10.
Before her arrest in June, prosecutors say Richardson -- an actress -- tried to frame her now-estranged husband for mailing the letters containing ricin, a powdery substance that can cause respiratory failure if inhaled.
The letter to Obama, according to a federal indictment, said: "What's in this letter is nothing compared to what ive got in store for you mr president."
An FBI affidavit filed in the case says Richardson first contacted authorities to implicate Nathan Richardson in the scheme, but later failed a polygraph exam and had inconsistencies in her statements to authorities.
Shannon Richardson, who had minor roles in the television series "The Walking Dead" and the movie "The Blind Side," later admitted she mailed the letters but maintained her husband made her do it, according to the affidavit.
Prosecutors last week filed a notice that a plea agreement had been reached. A spokeswoman for the U.S. attorney's office did not return a phone message Monday.
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