it all herself. two years earlier, she had to search for her murder daughter, amber dubois. now, carrie ran a search organization, in the memory of her daughter. she couldn't know, back then, the role she would play. the events she would set in motion. for now, it was who she knew. >> i put them in touch with mark, because it was up in northern california. they were all up in the same area. >> mark class, a rare man, with a rare skill. how to find the missing. >> coming up, a man who knows how it feels to lose a daughter, and had learned, from personal experience, how to lead the search. >> we need help from the police, and we finally said, that is where the cell towers take us. >> when dateline continues. >>