Investigators search a property that borders Phillip Garrido’s home Friday in Antioch, Calif. Police are searching for a possible connection between Garrido, charged with kidnapping Jaycee Dugard, and two other child abductions in the 1980s.

Antioch, Calif. ? The property where Jaycee Dugard was held captive for 18 years became the site of an archaeological-style dig Friday as authorities revealed the discovery of another bone and a soil “anomaly” that could indicate something lies buried in an area where cadaver dogs earlier picked up a scent.

Police from the cities of Dublin and Hayward have been searching the land to see if Phillip and Nancy Garrido, the couple charged with kidnapping Dugard in 1991, can be tied to two other Northern California child abductions from the late 1980s.

They cautioned that it was too soon to know whether the bone — one of several fragments recovered from the Garrido property and a neighboring parcel — or the presence of disturbed soil that indicates previous spadework were related to any crimes.

“It could be a lot of different things. It could be significant, and it could not be significant, but it’s helping us target where we might do some digging,” said Hayward Police Lt. Chris Orrey.

Orrey said Dugard, who was snatched outside her South Lake Tahoe home in 1991, has not supplied any information to indicate the Garridos were involved in the 1988 kidnapping of 9-year-old Michaela Garecht outside a Hayward market and the 1989 disappearance of 13-year-old Ilene Misheloff in Dublin.

“She’s not saying anything that helps us solve our case,” Orrey said. Hayward and Dublin authorities have not directly interviewed Dugard, but have asked other law enforcement agencies involved in her case to ask questions for them, she said.

Investigators nonetheless spent a fourth straight day combing the Garrido’s land and a neighbor’s yard for clues, a search they expect to resume on Monday.

Bill Silva, a professional archaeologist who has led excavations for ancient skeletal remains and historical artifacts in California, has spent the last two days pushing a ground penetrating radar in a grid pattern around the Garrido property.

On Friday, he picked up signs of disturbed soil that could indicate a pit where previous digging has occurred. Two cadaver dogs picked up a scent that may be a sign of remains in the same area on Thursday.

“We have set it up just like an archaeological site, where we are looking for real ephemeral remains,” Silva said of the backyard dig in Antioch. “This is the first crime scene I’ve worked on, unless you consider a Native American massacre site.”

If there was previous digging on the property, it could be due to something as simple as the fact that the neighborhood used to be made up of citrus orchards and walnut groves, he said.

The next step is to bring in two sets of dogs — one trained to sniff out decomposing bodies and the other trained to detect older bones, Orrey said.

Dugard, now 29, was reunited with her family Aug. 27, a day after her alleged captors were arrested. Phillip and Nancy Garrido have been charged with kidnapping and raping Dugard. Prosecutors say they hid Dugard in their Antioch backyard. The Garridos have pleaded not guilty.

Investigators already have dismantled the hidden encampment of sheds and tents where authorities say Dugard was held and lived with the two daughters she had by Garrido. They also removed 19 truckloads of debris from the yard and looked inside the Garrido’s house.

Orrey said they have taken “boxes and boxes” of papers in Phillip Garrido’s handwriting.

“We will have to take it offsite and go through every single page to see if there’s something significant,” she said.