and for ben tveidt it is the final tell in finding the missing link to his past. ion. >> dave cook. >> dave, nice to meet you. >> nice to meet you. >> reporter: believe it or not, he locates the detective who was one of the first on the scene three decades earlier. >> you didn't have any physical trauma, anything like that. the umbilical cord was tied off with a sandwich tie. >> reporter: the most promising lead that police sketch of a possible suspect never got an i.d. >> there were several possible prints but they were poor and not very useful. >> if fingerprints were lifted, would they have been preserved? >> we're talking 30 years now. and basically, all the photos have been destroyed. the prints have been destroyed. >> reporter: and yet again, old school crime solving is futile, leaving it for cutting-edge dna technology to save the day. the genealogist cece moore's been able to identify two of ben's second cousins. she traces their family trees all the way to their great-grandparents, then builds the family trees forward with their descendants, poring over ob