Shannon Richardson, 35, was named in a three-count indictment by a federal grand jury Thursday. Richardson is charged with threatening the president and mailing threatening letters to Bloomberg and Bloomberg's top gun control advocate Mark Glaze.
The letter to Mr. Obama was intercepted by a White House mail screening facility in late May. The letters to Bloomberg and Glaze were sent around that same time. The Secret Service confirmed the apparent link among the letters.
The letters did not harm any of the intended recipients, but three emergency responders who examined one of the letters did experience minor symptoms.
Richardson was arrested in Mt. Pleasant, Texas, June 7. Richardson reportedly told FBI agents her husband had sent the letters, but officials questioned her credibility after interviewing her. John Delk, who represents her husband, Nathaniel Richardson, says they believe she was trying to set him up. Nathaniel had recently filed for divorce.
If convicted, Richardson faces up to five years in prison on each charge.
Richardson has had minor roles in TV series, including "The Walking Dead" and "The Vampire Diaries." Shannon has five children ranging in age from 4 to 19 from other relationships and is pregnant with a child by Nathaniel.
The Associated Press and ABC News contributed to this report.