along. her unborn son died when she did. crystal had told friends the father of her child was a guy named derek smyer. so you want to find out where derek is. >> most definitely. we want to find everything about him right now. >> the detective learned crystal and derek had a quick fling. it only lasted a month or so. they'd met at anderson park, which is near both their jobs. by now, it was lunch time. derek wasn't in his office. so williams drove to the park. bringing crystal's work friends with him. and one of them immediately noticed something. >> she points out a car that derek drives. >> reporter: his car was easy to spot. it had vanity plates that said "my whip," slang for a fancy car. then crystal's friend pointed out derek. and detectives brought him in for a talk. >> go ahead and compose yourself. what is your last name, sir? >> smyer. >> and your first name, sir?