>> reporter: which gave detective lopez an idea. >> if he is that close to see that she is totally distraught, then she should have a pretty good look at who he was talking to. >> reporter: at the time no one had thought to show jana poletto a photo of c-styles, but now they did. and she said -- >> "that's who derek was talking to in the park." >> reporter: that was the missing link -- a witness who could connect c-styles to derek smyer. then one last piece. the d.a. wanted c-styles interviewed again. >> how are you? >> fine, and you? >> good, good. i'm danette meyers, i'm the d.a. >> reporter: this time they made sure what he said could be used in court. >> you have the right to remain silent. do you understand? >> yes. >> reporter: c-styles told the same story with the same details. how he met derek and how derek wanted help with crystal taylor. >> do you talk about when you're going to kill her? >> i told him i was going to do