Overview: When Chelsea Rustad uploaded her DNA to a public database hoping to find other branches of her family tree, she never expected that process would prompt a visit from police investigators. The police were at her Washington state home with devastating news - someone in her family may have committed a double murder. 48 HOURS and correspondent Erin Moriarty immerse viewers in the case of a killer who eluded police for 31 years, then was identified in just two hours by genetic genealogist CeCe Moore.