Shannon Guess Richardson entered her plea in federal court in Texarkana, Texas, to a federal charge of possessing and producing a biological toxin, news.com.au reports.
Richardson was arrested in June after authorities said she tried to implicate her husband, Nathan Richardson, after he had filed for divorce.
Prosecutors said Richardson mailed three letters from New Boston then went to police and claimed that her husband had done it.
The 35-year-old played minor roles in the television series The Walking Dead and the film The Blind Side.
Prosecutors said investigators learned that she had purchased materials online to produce ricin, a toxin that can cause respiratory failure if inhaled, the report said.
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, it added.
--ANI (Posted on 11-12-2013)