Authorities in Texas now believe a pregnant actress who told FBI agents that her husband had mailed letters tainted with ricin had really carried out the scheme herself.

    The letters were sent to President Barack Obama and to New York Mayor Michael Bloomberg, and to his gun-control group in Washington.

    It's not clear yet what charges will be filed against Shannon Richardson of New Boston, Texas. She's described as a mother of five who has played bit roles in TV shows. Her arrest was confirmed by two law enforcement officials.

    A lawyer for her husband, Nathaniel Richardson, had earlier told the Associated Press that his client had filed for divorce, and that he may have been set up by his wife. He said Nathaniel Richardson was cooperating with authorities investigating the letters, which had warned of violence against gun-control advocates.

    The FBI is investigating at least three cases over the past two months in which ricin was mailed to Obama and other public figures.

    If it's inhaled, ricin can cause respiratory failure. If it's swallowed, it can result in death. (Associated Press)