keith morrison: 15 years later, detective donna velasquez relived that puzzling time. n arizona, as she told detective velasquez, got a call from david's worried mother. barbara said she wasn't worried. not then. i thought, ok, he was with one of his girlfriends. and she was like, no, we're doing a missing person report. and i said, no, he's going to call me in a couple days. i know he is. he's gonna call me in a couple days. and he never called. he never called. keith morrison: one day turned into the next. police, family, everybody tried to find him-- couldn't. started looking, searching through canals, swam in through pipes, under the little bridges on the little dirt roads. anywhere. if you'd see a car that looked like his go by, you'd do a u-turn and you chased it. how long did that go on? that went on until they found his car. keith morrison: which, more than three months later turned out to be at the airport. so did he just take off? his close friend didn't think so. maybe he got on a plane, and maybe he wanted to do something different. and then it was like, no,