(CNN) -- — A Texas actress charged with sending ricin-tainted letters to President Barack Obama and New York Mayor Michael Bloomberg was found competent Wednesday to stand trial.
Appearing in federal court in Texarkana, Texas, Shannon Richardson, 35, entered a plea of not guilty to all counts.
Richardson, also known as Shannon Rogers and Shannon Guess, initially told the FBI that her husband, Nathaniel, had sent the ricin-laced letters, but a polygraph exam found her to be "deceptive" on the matter, authorities have said.
Investigators found that her computer storage devices contained the text of threatening letters sent to the president, but the couple's computer records show that her husband couldn't have printed them out because he was at work at the time, according to an FBI arrest affidavit.
Richardson later told investigators she mailed the ricin-tainted letters, but she claimed that her husband typed the letters and forced her to print and mail them, the affidavit said.
Her husband denied involvement and claimed that his wife wanted to end their marriage and leave him. He told investigators that his wife was "intentionally misleading" them, court papers said.
Nathaniel Richardson has filed for divorce. His wife is pregnant, according to divorce papers.
Richardson has had minor roles in TV series including "The Walking Dead" and "The Vampire Diaries."
CNN's Joe Sutton, Dana Ford, Chandler Friedman and Chelsea J. Carter contributed to this report.