>> he went out there a with friend of his and they saw johnny for three days. i got pictures of johnny in, like, the old western town and everything. >> reporter: and maybe it was something about the distance, said barbara -- >> david and i became very good friends when i was out in arizona. and we used to talk a lot. >> reporter: in fact, what she felt deep in her heart, she said, never did go away. >> i'll always love david. >> reporter: and then it was june 25th, 1988. david's brother mark was flying into town to visit the family. david was to pick him up at the airport. but when mark arrived, he waited. and waited. no david. and mark jackson had a terrible feeling. >> no matter what, he'd have been there for me. i knew something was wrong. i knew something bad happened. >> reporter: oh yes, very bad. and as the rookie detective donna velasquez poked around deep in the past, that something was reaching up through the mud to tell her its long neglected story.