we would have never thought of that on our own. keith morrison: klaas even flew in his director of search operations who was one of the first volunteers to look for polly years before. we're going to be dealing in some pretty treacherous terrain today as well as tomorrow. canyon areas, lots of rocks into the ravines. keith morrison: this was day 49 since michelle disappeared. and once again, her san diego relatives loaded into cars around midnight and drove the eight hours north to the san francisco bay. "dateline" was there watching as they gathered for a morning briefing to prepare them for the long day of searching ahead. if you take nothing else away from this presentation, take this portion right here, ok. every single search that we put you on today, tomorrow, we consider a potential crime scene. keith morrison: the police suggested a zone to be searched, but that's about all the information they provided. we don't know exactly why, but they say it's based on all the evidence and their timeline they believe that something might