Man hunt stretching from canada to mexico now zeroing in on a rugged mountain. The fbi in force. Gio benitez has been tracking the race to find a missing girl and the suspect. Reporter: A desperate... See More
Man hunt stretching from canada to mexico now zeroing in on a rugged mountain. The fbi in force. Gio benitez has been tracking the race to find a missing girl and the suspect. Reporter: A desperate search under way in a idaho wilderness area. The u.S. Customs service and border protection now joining the fbi. 16-year-old hannah anderson and her alleged kidnapper, james DiMAGGIO WERE SPOTTED HERE, Known as the river of no return. They were spotted twice. They had backpacks on, they spotted a tent, and so they were obviously camping in that area. Reporter: Police say DiMAGGIO, A CLOSE FAMILY FRIEND Of the andersons' is an outdoors man. Four horseback riders who saw anderson and the 40-year-old say they had light camping gear. I think we should all be optimistic that she appeared to be in somewhat good health, and was alive on wednesday. Reporter: The preserve is about 70 miles from boise. Nearby, authorities found DiMAGGIO'S BLUE NISSAN VERSA Covered with brush. He's accused of killing the teenager's mother and possibly her 8-year-old brother and setting his san diego home on fire and abducting anderson. Police say he could have been infatuated with the 16-year-old. If she's still alye, and apparently two days ago, she was. He may want to protect her. Reporter: This was the first time if california that an amber alert was sent out to millions of people on cell phones. The teen's father making a plea this week. I'm begging you to let my daughter go. You've taken everything else. Reporter: Agent will be sent into that area tonight. And now, we turn to a baffling and beautiful rescue.
This transcript has been automatically generated and may not be 100% accurate.