ANTIOCH, Calif. (CBS/AP) Is evidence of foul play about to be unearthed in a place already believed to have been a house of horrors for at least one kidnapped child?
Authorities investigating two missing girl cases said Thursday that cadaver dogs picked up a scent in the backyard of Philip and Nancy Garrido that could indicate buried remains on the property of the couple already charged with the kidnapping and rape of Jaycee Dugard.
Alameda County Sheriff's Department spokesman Sgt. J.D. Nelson said two dogs "indicated" on a site in the Garridos' backyard. But he cautioned that the area is known to have buried remains from Native Americans and animals.
Authorities from Hayward, Calif. are seeking any evidence on the property that may link the Garridos to the 1988 abduction of Michaela Garecht outside a Hayward market. Dublin, Calif. police are looking for clues that may tie the couple to the 1989 disappearance of Ilene Misheloff.
The Garridos are charged with kidnapping Jaycee Dugard in 1991. The South Lake Tahoe girl was 11 when she was snatched outside her home. Prosecutors say the couple held her captive in a makeshift encampment in their backyard for 18 years.
The Garridos have both pleaded not guilty.
Since the Garridos' Aug. 26 arrest, their Antioch home has become a focal point of investigators reviewing outstanding kidnapping cases in the San Francisco Bay area. Their lawyers are not discussing the property searches.
Nelson would not say where in the yard the dogs picked up a scent and warned of false positives.
Investigators planned to use high-tech radar equipment to scan the site on Friday. They would start digging if the radar gives more specific information about what is underground, Nelson said.
Cadaver dogs are trained to sniff for the scent of a decomposing body and can catch smells of up to two or three feet, Nelson said.
"They picked up a scent that may or may not be a sign of some remains," Nelson said. "The first dog was very tentative on its indication. The second dog was more direct and indicating directly."
On Wednesday, police recovered a bone fragment on the Garrido property and several more in a next door neighbor's yard that also was being searched by investigators because Phillip Garrido had access to it.
Tests are being done to determine if the bones are human or animal, officials said.
Investigators continued clearing trash and brush from the backyard that was outfitted with tents, sheds, an above ground pool and showers, and have collected personal items that they wouldn't identify that they say belong to Dugard.
THE JAYCEE LEE DUGARD STORY
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More on the Jaycee Dugard investigation on The Early Show.
Body Buried in Garrido Yard?