Richardson was abandoned by her mother at the age of two and raised by her father, Terry Rogers. Rogers worked at General Motors in Doraville, Georgia. She was the oldest of three children, having one younger brother and one younger sister. At the time of her arrest, Richardson lived in New Boston, Texas. She has been married three times. On October 8, 2011, she married Nathan Richardson, a U.S. Army veteran who works as a mechanic in a military depot. He filed for divorce in June 2013.

At the time of her arrest in June 2013, Richardson had five children, ranging in age from 4 to 19 with her two previous husbands and was pregnant with her sixth child. On July 4, 2013, Richardson gave birth to a boy, named Brody, while in custody. Officials said that the baby was born four months prematurely, weighed only two pounds at birth, and that he needed to remain hospitalized. In August 2013, Nathan Richardson won temporary custody of Brody.

In May 2013, while going through a divorce, Richardson called the police and falsely accused her husband, Nathan Richardson, of mailing letters laced with the poison ricin to several politicians. Nathan Richardson was never charged in regard to the matter. He told investigators that his wife set him up. Investigators found evidence that she had mailed the ricin-laced letters herself in an effort to set up her estranged husband.

Richardson was arrested on June 7, 2013, for her alleged involvement in ricin-laced letters being sent to politicians such as President Barack Obama and New York City mayor Michael Bloomberg. She was charged with “mailing a threatening letter to President Barack Obama”.

On November 22, Richardson reached a plea agreement on three counts. On December 10, she pleaded guilty and was sent to the Texas State Prison System. The U.S. government contracts with county and state officials nationwide to hold federal prisoners pending trial. On July 16, 2014 most of the charges against Richardson were dropped as per her plea agreement. The charges of making threats against the President of the United States and mailing threatening communications were dropped. Richardson was convicted of the charge pertaining to manufacture and possession of a biological weapon and sentenced to 18 years in prison, $367,222 in restitution, $100 special assessment fee (for psychological testing), 5 years’ supervised release and ordered to undergo psychological treatment while in prison and continue psychological treatment after her release.

On March 16, 2015 the Investigation Discovery channel aired episode 10 of season 6 of the television show Who the (Bleep) Did I Marry? which featured Shannon Richardson’s case as told by her ex-husband. The episode was titled “Poison Love”.

In March 2015, Shannon Richardson filed suit under 42 U.S.C. § 1983, for deprivation of rights while imprisoned. The civil action was “dismissed with prejudice” on 7 March 2015.