(CNN) -- A Texas woman pleaded guilty Tuesday to a biological weapons charge after she was accused of sending ricin-laced letters to President Barack Obama and New York City Mayor Michael Bloomberg, prosecutors announced.
Shannon Guess Richardson, 35, pleaded guilty to possession of a toxin for use as a weapon, prosecutors said in a statement.
She could be sentenced to up to life in prison. A sentencing date has not yet been scheduled.
Richardson, an actress, was accused of sending the letters earlier this year.
In June, a grand jury indicted her on charges of threatening the president, mailing a threatening letter to New York City Mayor Michael Bloomberg, and mailing a threatening letter to Mark Glaze, director of Mayors Against Illegal Guns, a group Bloomberg founded and co-chairs.