The appeals court on Wednesday returned Richardson's case to Tarrant County.
Attorneys for the 27-year-old Richardson argued prosecutors withheld evidence at her 2005 trial, and she deserved a new punishment hearing. Her trial judge agreed and the appeals court has agreed with that recommendation.
Richardson was convicted of masterminding the slayings of her boyfriend's parents, Rick and Suzanna Wamsley, of Mansfield, so her boyfriend could inherit their $1.56 million estate. She was 19 at the time of the December 2003 killings.
Her boyfriend, Andrew Wamsley, and another woman, Susana Toledano, are serving life prison terms.