Finding Grace

There are an estimated 250,000 unsolved murders in the US, and in many of them, the victims are yet to be identified. But now, recent breakthroughs in DNA technology and the growth of genealogy websites are beginning to unlock the secrets of cold case murder investigations. That can bring a form of closure to the families of victims - but does it also come at a cost to our privacy? James Clayton travels to Kansas to discover how cutting-edge science identified a woman killed 30 years ago and is now helping law enforcement hunt for the killer.