On January 16, 1980 Helene Pryszynski leaves her intern job at local radio station in Denver, Colorado. She takes the bus to her stop near her aunt's house where she is staying. It is just a 6 block walk home when she disappears. She never made it home and was found brutally murdered the next day. It would take 4 entire decades before this murderer was caught.
Sources for this episode include a Dateline episode entitled A Promise to Helene.