ANTIOCH, California (CNN) -- Two cadaver dogs working separately each showed interest in the same area of property belonging to kidnapping suspects Phillip and Nancy Garrido, a possible indication of human remains, police said Thursday.
Police search for evidence relating to missing girls Ilene Misheloff and Michaela Garecht.
Authorities will use ground-penetrating radar equipment on Friday to examine the area, and "we will eventually be digging in that location," said Hayward police Lt. Chris Orrey.
The Garridos face a combined 29 felony counts in the 1991 kidnapping of Jaycee Dugard, then 11, from South Lake Tahoe, California. Authorities believe the couple held Dugard in a hidden compound behind their home for 18 years and have said Phillip Garrido, a registered sex offender, fathered her two children.
On Tuesday, police from Hayward and Dublin, California, began executing search warrants simultaneously on the Garrido property and an adjacent property to which Garrido had access.
They are seeking any evidence in the 1988 abduction of 9-year-old Michaela Garecht of Hayward and the 1989 disappearance of 13-year-old Ilene Misheloff of Dublin. Both agencies have said that while Garrido has not been named a suspect in either case, he cannot be eliminated as a suspect. Watch police search the Garrido home »
On Wednesday, authorities said they had found bones on the Garrido property as well as the adjacent property but do not know whether they are animal or human. The bones are being analyzed, Orrey said on Thursday, and no new information was available about them.
In addition, a bone fragment was found on the adjacent property last week. Police said it was probably human, and it is being tested at the state DNA lab.
Police said the spot that the dogs showed interest in was in "open ground" on the Garrido property. The first dog gave a tentative indication of something there, so the second dog was brought in and made a more definite indication, said Sgt. J.D. Nelson of Alameda County Sheriff's Office. The dogs, which undergo between six months and a year of training, are trained to find human remains.
It is possible for the dogs to give "false positives," Nelson said -- a reason why the second dog was brought in. However, since both dogs showed interest, going forward with the other methods is recommended, he said.
Orrey said the digging could begin as soon as Friday, but was not sure when it would occur.
Police have disassembled some horse sheds and a deck on the properties, Orrey said, and plan to overturn the concrete slabs they were built on in order to have the dogs check the spots out. There are other slabs on the property as well, she said, some of which are "randomly placed" and "piqued our interest," she said.
Police also have taken some things for Jaycee and her family, and "a few things we want to take a second look at," she said, adding, "nothing compelling so far has been taken." Officers are "doing a lot of photo-documentation" in case anything turns out to be connected to another case, she said.
The operation may wrap up midweek next week, Orrey said. The home is in unincorporated Contra Costa County, near Antioch, California.
Meanwhile, officials at Contra Costa County Animal Services Department said Dugard and her daughters will be reunited with pets taken from the Garrido home after he and his wife were arrested in late August -- five cats, two dogs, three cockatiels, a pigeon, a white mouse and a parakeet.
Officials said the animals appeared to be well cared-for. It was unclear when Dugard would get them back.
CNN's Dan Simon contributed to this report.