he was very obsessed with angie. craig melvin (voiceover): the trail went cold for more than two decades, but she was sure she knew who the killer was, even got a private detective license to help prove it. i said, i'm a private investigator, and i need you to tell me where's the evidence, all of that. it wasn't well received at all. craig melvin (voiceover): finally, the break they needed. we got the match. craig melvin (voiceover): leading to one of the greatest twists of all time. you could not have shocked me more. [music playing] hello, and welcome to "dateline." when angie samota walked into a room, people noticed. pretty, vivacious, and outgoing, the college student had her choice of dates. then late one friday night, angie was murdered. a crucial clue pointed to one man. but in this case, nothing was as it seemed. it would take decades and a tenacious friend to uncover the truth. here's josh mankiewicz with "in the middle of the night." [music playing] josh mankiewicz (voiceover): it was a saturday morning in octob