(CNN) -- In the middle of the Idaho wilderness, a man on horseback had a brief conversation with two campers. The rider's realization later that he may have been talking to California Amber Alert suspect James DiMaggio and his alleged teenage captive has now focused a nationwide manhunt for the pair on the rugged mountain area in central Idaho.
The horseback rider saw the man and girl Wednesday and struck up a brief conversation with them, Andrea Dearden, spokeswoman for the Ada County Sheriff's Office, said Friday.
He was not aware of the manhunt at the time, but he called the Amber Alert tip line after he saw a news account that night and realized the pair matched the description of DiMaggio and 16-year-old Hannah Anderson, she said.
The rider's impression of the pair was "it seemed odd but nothing as alarming," Dearden said.
"They did speak and exchange pleasantries. I don't think there was a lot of information exchanged," she said. "He left the conversation believing they were camping in the area."
The rider said the man and girl were on foot, hiking with camping gear, Dearden said.
Dearden appeared to be correcting authorities' earlier reports that the suspect and girl were spotted by more than one horseback rider.
Investigators set up checkpoints where DiMaggio and Hannah were believed to be traveling in the River of No Return Wilderness area, about 15 miles outside Cascade, Dearden said.
Authorities haven't yet evacuated any homes or businesses, she said, adding, "We have those access points secured."
The horseback rider's tip moved the national manhunt for DiMaggio and Hannah, who was last seen Saturday afternoon at her cheerleading practice, to the Idaho mountains.
Authorities in Southern California began looking for Hannah after their mother was found dead inside DiMaggio's burned-out house in the San Diego area Sunday. Late Friday, authorities said lab tests confirmed that a second body found in the house was that of Hannah's 8-year-old brother, Ethan.
DiMaggio was a close friend of the Anderson family, and father Brett Anderson has appealed to DiMaggio to let his daughter go.
Friday morning, investigators found DiMaggio's car hidden by brush, its license plates removed, about six to eight miles from where the rider spotted the girl, authorities said.
They confirmed the car's ownership by its vehicle identification number, he said.
The vehicle will be examined by bomb and arson technicians to ensure it's not rigged with explosives, Gore added. His office has said evidence found at the burned house indicates that explosives may be in the car.
The horseback rider said the man and girl appeared to be in good health, Gore said.
Suspect 'capable of anything'
Authorities deem DiMaggio a dangerous suspect because he is accused of killing Hannah's mother, Christina Anderson, and possibly Ethan as well.
The second body is so badly burned that carrying out a DNA test is proving difficult, authorities said. The sheriff's office is treating Ethan as a missing person until they can identify the body.
A search of DiMaggio's burned-down house led law enforcement to this conclusion: "We don't hold anything past this person," as one official put it.
"We think that he's capable of anything at this point," said Capt. Duncan Fraser of the San Diego Sheriff's Office.
Based on what the sheriff's investigators have seen, there is evidence that the fire and kidnapping of Hannah was a "very well-planned event," Fraser said.
Idaho on Friday became the latest state to issue an Amber Alert for Hannah, following California, Oregon, Washington and Nevada.
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The San Diego Sheriff's Department already said it was possible DiMaggio was hunkered down in a rural area because he is a camper.
"We've got law enforcement agencies across the country looking for them and following up on tips that are being called in," San Diego County Sheriff's Department Lt. Glenn Giannantonio told CNN on Thursday. "We've received numerous tips, I'd say probably well over 100, possibly hundreds of tips from across the country. Every tip that can be followed up on has been followed up on or is currently being followed up on."
Suspect is family friend
DiMaggio was described as being so close to the Andersons that he was considered part of the family, Brett Anderson told CNN's Chris Cuomo on Thursday. He came into their lives before Hannah was born.
DiMaggio was such good friends with the family that Anderson said he can't reconcile the man he knows with the crimes he is suspected of.
"I have been through every scenario in my brain," Anderson said. "There was nothing ever to show any indication of this."
DiMaggio joined the family on campouts and was always friendly toward them, he said.
"I can't fathom what happened in Jim's head. He obviously just lost it," Anderson said.
"You've taken everything," the father pleaded to DiMaggio in the interview. "The damage is done. Just let my daughter go, Let her go home safe, let her be with me and try to mend things from there."
Some witnesses have told investigators that DiMaggio had a crush on Hannah, but Brett Anderson has said the family had no knowledge of that.
Fraser said that they are looking into whether the suspect possibly had an "undue infatuation" with the teen.
Michael Martinez and Mariano Castillo, CNN