It was not immediately clear what charges would be filed against Shannon Richardson of New Boston, Texas, for the letters. Two US law enforcement officials confirmed her arrest to The Associated Press but spoke on the condition of anonymity because they were not authorised to speak publicly during the ongoing investigation.
FBI agents wearing hazardous material suits were seen going in and out of her house Wednesday in New Boston, northeast of Dallas near the Oklahoma and Arkansas borders. Officials have said the search was initiated after the resident's spouse contacted the FBI.
It was not immediately clear if Shannon Richardson, an actress and mother of five children, has an attorney. Her resume on the Internet movie database IMDb said she has had small television roles in The Vampire Diaries and The Walking Dead. She also had a minor role in the movie The Blind Side and appeared in an Avis commercial, according to the resume.
Delk said Richardson came to him to discuss a potential divorce a year ago and finally hired him on May 6, weeks before the ricin incident came to light.