leslie mahaffy. night that leslie disappeared, she had attended a memorial for a young gentleman who was killed in a car accident. garofalo: she got home at 2:00 in the morning. all the lights were off. kenzora: the door was locked. she left and went to a phone booth and called her friend to say, "i'm locked out. can i come stay at your house?" friend said no, so she walked back to her house. kenzora: and that was the last anyone heard from her. hemsworth: and everyone had hoped for the best, and then everyone discovered the worst. reporter: the dismembered remains of 14-year-old leslie mahaffy were found in a nearby lake. she had disappeared two weeks before. hemsworth: her body had been dismembered, encased in pieces of concrete. and i still was hoping that maybe the police had made a mistake. but it was her. and then another young girl goes missing. reporter: ten months later, another victim -- 15-year-old kristen french. she was kidnapped in broad daylight. ♪ pron: she passed by a church. there w

actually, a few hundred yards from the grave of leslie mahaffy. ody was found. so it was clearly some kind of message. i think everyone knew at that point that there was a serial killer on the loose. reporter: police are not discounting the possibility a serial killer may be at work in the area. as the investigation continued, i got a call from vince bevan, who was in charge of the investigation. he had this unusual request from a tv station who wanted to know if they could be helpful in some way. could they do a documentary? so i said, "let's use this to our advantage. we can communicate with the offender." because we know in any of these cases, these high-profile cases, these offenders follow the media. gregg, if he is watching this program tonight, what do you think he might be experiencing? don mclean, he asked me, "well, if the offender is watching now, what would you say?" i said, "if he's listening, i want to tell him you're going to be apprehended." it's just a question of when. kenzora: and he was watching. garofalo: he lived in a pretty,