The case of Katherine Cardenas was one that will be not be forgotten. The two-year-old was brutally raped and killed back in 2009. Jose Eduardo Arredondo was found guilty earlier this year in that case and was sentenced to four life terms in prison. But one charge against Katherine's mother, Norma Patricia Olguin, was still pending. The case of sexual assault against Olguin for having relations with her child's underage killer was dropped Tuesday morning. Arredondo was only 16 when they had relations. District Attorney, Isidro Alaniz said they made a deal with Olguin back in 2009; if she truthfully testified in Katherine's murder trial, they would drop the sexual assault charge. "As a prosecutor you have to prioritize the objective. In this particular case, we stand behind our decision on what we did here. It was interesting the way we found out the sexual assault on Jose Arredondo was through Norma Patricia Olguin's own statement." Alaniz said they would not have known about the sexual assault if Olguin did not tell them. He also said Arredondo never filed charges on Olguin and the charges were originally filed by the district's attorney's office. Olguin did previously serve two years in prison for child abandonment.