Police also on Saturday wrapped yellow crime scene tape around the property next door to the residence of Nancy and Phillip Garrido, who were arrested Wednesday on suspicion of abducting Jaycee Lee Dugard. The authorities called it a crime scene but declined to elaborate.
Neighbors identified the next door house as belonging to Damon Robinson, who has lived there for more than three years. Robinson's then-girlfriend in 2006 called police after she saw tents and children in the backyard. The responding officer failed to discover the encampment where authorities say Dugard was kept captive.
Robinson could not be reached. He earlier told The Associated Press that Phillip Garrido was the caretaker of the house until Robinson moved there in 2006.
Robinson earlier told CBS News station KPIX in San Francisco that when he moved into the house he thought it was strange that all of the doors locked from the outside as if they were rigged to lock people inside.
Neighbor Janice Deitrich, 66, also said that Phillip Garrido would visit and help feed an elderly neighbor who lived in the house before Robinson.
Phillip and Nancy Garrido are suspected of abducting Dugard 18 years ago and subjecting her to nearly a lifetime of torment in a squalid backyard compound. They pleaded not guilty Friday to a total of 29 counts, including forcible abduction, rape and false imprisonment.
The investigations are "preliminary," said Jimmy Lee, a spokesman for the Contra Costa County Sheriff's Department, east of San Francisco Bay, declining to say what past cases were being reviewed.
Police in Pittsburg are investigating whether Phillip Garrido, whose home is in nearby Antioch, is linked to several unsolved murders of prostitutes in the early 1990s. Antioch police are also looking into unsolved cases but declined further details.
About a dozen agents scoured the modest house and the acre of land it sat on Saturday afternoon as the temperature soared into triple digits.
Police spent most of the day searching the Garridos' backyard, where Dugard is alleged to have lived in tents and shacks with her two daughters fathered by Phillip Garrido. One officer could be seen scanning the backyard with a metal detector while another dug a hole. A third used a chainsaw to clear branches and investigators shuffled in and out of the property all day.
Officers from the Pittsburg Police Department, Antioch Police Department and the Contra Costa County Sheriff's Department were on hand.
The quiet working class neighborhood where the Garridos lived had transformed into a media circus of television trucks, wandering journalists and the simply curious, who began driving down the Garridos street once a police checkpoint into the neighborhood was removed.
Mike Rogers, who owns a storage lot next to the Garridos' back fence said that he occasionally heard loud parties coming from the backyard. Rogers said the parties were a mostly male affair.
Dugard, now 29, was reunited with her mother, sister and another relative Thursday. She is said to be in good health, but feeling guilty about developing a bond with Garrido, said her stepfather Carl Probyn. Her two children, 11 and 15, remain with her.
"Jaycee has strong feelings with this guy. She really feels it's almost like a marriage," said Probyn, who was there when little Jaycee was snatched from a bus stop in 1991 and has been in contact with her mother since they found out the girl was alive.
"Hi, mom, I have babies," was Dugard's first words to her mother when they were reunited Thursday, Probyn said.
She is now free thanks in large part to two quick-thinking police employees at the University of California, Berkeley. Garrido was on campus with his two daughters earlier this week saying he wanted to hold some sort of religious event.
Garrido seemed incoherent and mentally unstable, and the girls wore drab-colored dresses, were unusually subdued and had an unnaturally pale complexion, said Lisa Campbell, a special-events unit manager with UC Berkeley's police department.
Garrido's parole officer was alerted. On Wednesday, Garrido arrived at the probation officer's building with his wife, the two girls and a woman who initially identified herself as Allissa - who was in fact Dugard. Investigators said Garrido confessed to the kidnapping.
Garrido managed to avoid detection over several years and some close calls.
After his release from prison on an earlier kidnapping charge, Garrido met with his parole agent several times each month and was subject to routine surprise home visits and random drug and alcohol tests, California Department of Corrections and Rehabilitation spokesman Gordon Hinkle said. The last unannounced visit by a team of local police agencies was conducted in July 2008.
"There was never any indication to my knowledge that there was any sign of children living there," Hinkle said.
The heavily wooded Antioch compound was arranged so that people could not view what was happening, and one of the buildings was soundproofed.
Complete coverage from Crimesider:
Cops Search Suspect's Home for Evidence of Murdered Prostitutes
Photos: Little Girl Found 18 Years Later
Forensic Psych: Does Garrido Really Believe Kids Cured Pedophilia?
Why Didn't Neighbors Know?
Exclusive: Reporter Remembers Girl's Abduction 18 Years Ago
Garrido: Dugard's Girls "Slept in My Arms Every Single Night"
Legal Analysis: Statute of Limitations Non-Issue in Prosecuting Alleged Captors
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