Police expand their search for Christa Worthington's killer, looking at an ex-boyfriend and even Christa's own father. But a match on a crucial piece of D.N.A. evidence continued to be elusive, forcing police to take an unorthodox approach to find the killer and one that would grab national headlines. Support this podcast with a review --------> http://bit.ly/2xj9fk8 *** Can you help catch a killer? Check out our other series, "A Murder On Orchard Street." Listen and subscribe: http://apple.co/2xuXURv *** ** Subscribe to "Start Here," the new daily podcast from ABC News, available on Apple Podcasts (https://apple.co/2pvq8Ws), Google Podcasts (http://bit.ly/2JZSK70), or your favorite podcast app! "A Killing On the Cape" is a production of ABC Radio and ABC News "20/20." Subscribe to the weekly "20/20" podcast on Apple Podcasts (http://apple.co/2zKPW5c) or wherever you're listening right now. Find more ABC podcasts at http://www.abcnewspodcasts.com