A Texas actress has been indicted for allegedly sending ricin-laced letters, including one to President Obama.

A federal grand jury accused 35-year-old Shannon Guess Richardson of threatening the president and mailing threatening letters, according to the U.S. Attorney's Office for the Eastern District of Texas.

The toxin ricin can cause respiratory failure or shut down the liver and other organs.

Letters were sent to Obama, New York City Mayor Michael Bloomberg and Marke Glaze, the director of Mayors Against Illegal Guns.

Richardson, of New Boston, Texas, has had roles in The Vampire Diaries and The Walking Dead on television. She also played a minor part in the movie The Blind Side.

She was arrested in connection with the letters earlier this month.

Prosecutors say she could face up to 15 years in prison if convicted.