in 2006 cold case detectives began working with prosecutors kristin richardson and carla carlstrom.tigators dug deeper into cliff reed's story. >> they were learning more, and more and more about cliff's lies, and sort of his relationship with sandi and some specifics about that day that didn't add up. >> reporter: for instance, sandi had taken that friday april 26th off work to get ready for sean's birthday. among her errands, she told friends, she was picking up a birthday present for sean from cliff reed. >> cliff reed never acknowledged that sandi was to come to his house that day or had ever come to his house that day. >> he said he had last seen her two weeks before. >> reporter: what's more, cliff reed's neighbor told police sandi must have been there that day. >> the neighbor saw her car, recognized her car parked outside his house. >> reporter: that was troubling to police. but more incriminating was this -- that same neighbor said he saw cliff reed driving sandi's car away from the apartment that day. and that grocery store lot where sandi's car was found? it was within wa