in her heart never did go away. >> i'll always love david. >> 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. >> oh, yes, very bad. and as the rookie detective donna velasquez poked around deep in the path, that something was reaching up through the mud to tell her its long-neglected story. >> the case was both cold and baffling. but maybe mother nature in south florida could help the investigation. coming up -- >> with the crazy weather and the water table that we have, if he were ever buried anywhere, somewhere along the line, you're