colgate total for whole mouth health. >> reporter: fbi agent craig overby was looking at nicole waller'sd expedition. it had been found packed full of her belongings and abandoned, on montana's fort peck indian reservation, about a mile outside the small town of poplar. then overby heard something strange. the agent walked around to the back door. opened it. >> there were two guinea pigs in the very back cargo area of the expedition. the two guinea pigs were making squealing noises. >> they hadn't been fed in a while probably. >> that's right. and i was really surprised they were alive. the car had been there for a few days. and it was 5 degrees outside. >> reporter: would nicole, the girl who'd loved animals, have walked away from those family pets? it seemed unlikely. but the fbi knew nothing yet about nicole. only, a highway patrolman's report that her expedition had been sitting there for four days. and, that she was nowhere to be found. >> the highways here in montana are long and desolate. if you stop here, if you break down here, if you're forced off the road here, it might be a l