Shannon Richardson, the former actress who appeared briefly on shows like The Walking Dead and The Vampire Diaries, pleaded guilty in Texas Tuesday to sending letters laced with ricin to President Obama and New York Mayor Michael Bloomberg. The plea deal mandates that Richardson spend up-to 18 years in federal prison on charges of possessing and producing a biological toxin, according to The Hollywood Reporter.

Richardson, 35, was arrested in June after she tried to get her estranged husband, Nathan Richardson, charged with the crime. Investigators soon learned that Shannon Richardson was behind the letters after finding out she had bought the materials to make ricin online.

In the plea document presented to the court, Richardson wrote, "I printed the mailing labels for President Barack Obama, New York City Mayor Michael Bloomberg, and Mark Glaze with The Raben Group."

In the letters to President Obama, Richardson wrote, "What's in this letter is nothing compared to what ive [sic] got in store for you mr[sic] president." She continued, "You will have to kill me and my family before you get my guns.”

While Richardson could spend 18 years in prison, we won’t know the final sentence until a later hearing.

[via The Hollywood Reporter]