lester holt (voiceover): but nassau county police didn't budge. they felt the evidence against seemona was overwhelming. and as she languished in jail for months, one thing kept eating at her, something that happened the night she was taken into custody. at one point during the interrogation, i noticed that there is a folder, like manila folder, this high, and on top of it is his picture. whose picture? jerry's. they have a folder on him. so i spilled my guts about the rape, everything i know about jerry and what's going on. and the detective casually just says to me, well, this is not about him. i'm thinking to myself, how could this not have anything to do with him? natalie morales (voiceover): coming up, a new witness comes forward and upends the entire case. she decided to go to the nassau da's office and come clean. natalie morales (voiceover): when "dateline" continues. steve chooses to walk over the26.2 miles,9 days... that's a marathon. and he does it with dr. scholl's. only dr. scholl's has massaging gel insoles that provide all-day comfo