call, from a guy named marty. marty rossler. reporter: and what does marty say to her? marty says he befriended lynsie, he s a friend of lynsie s and he s concerned because he hadn t heard from her. reporter: what did you learn about marty rossler? marty rossler was not marty rossler. reporter: marty rossler was really marty pregenzer. he did not have a criminal record. what he did have was a relationship with lynsie he hadn t told his wife about. he told police he often picked lynsie up and give her rides, but that was about it. marty was 58. and she was 20? she was 20. reporter: they were boyfriend and girlfriend? don t think so. reporter: so police brought in marty. over two days they recorded those interviews. at times on video and sometimes just on audiotape. when is the last time you saw lynsie? a week ago. no. i don t think so.
at your wit s end at this point. yes. reporter: and the phone rings, and it s a guy named marty. uh-huh. reporter: did you know a marty? no. reporter: as far as you know, did lynsie know a marty? no. reporter: marty told nancy that he d gone to pick up lynsie at school, but she wasn t there. he said he had money of lynsie s that she needed for tuition. none of that made any sense to nancy. after lynsie goes missing, nancy, her mother, gets a phone call from a guy named marty? marty rossler. reporter: and what does marty rossler say to her? marty says that he s befriended lynsie. he s a friend of lynsie s and he s concerned because he hadn t heard from her. reporter: but what did you learn about marty rossler? marty rossler was not marty rossler. reporter: marty rossler was really marty pregenzer. he did not have a criminal record. what he did have was a relationship with lynsie that he hadn t told his wife about. he told police he d often pick lynsie up, and