A man charged in the killings of a man and his pregnant wife to keep them from testifying in a San Diego drug trafficking case pleaded guilty to federal charges Monday. The investigation into the drug smuggling led agents to Yakima, where investigators interviewed Murillo and Hernandez in August of 2022. Madrigal-Birrueta's plea agreement states that he and other co-conspirators fatally shot Murillo on Aug. 28, 2022, at a ranch just outside Yakima. The plea agreement states Madrigal-Birrueta maintains that Murillo also fired gunshots at him and his co-conspirators, though no one was struck by that gunfire. Along with admissions to his involvement in Murillo and Hernandez's killings, the plea agreement states he caused the death of the couple's unborn child.