They're also looking next door, where a human bone fragment was found on a previous search, because Garrido had access to that property. They're wondering if he had anything to do with two other missing girls.
Michaela Garecht, 9, of Hayward disappeared in 1988 and 13-year-old Ilene Misheloff of Dublin has been missing since 1989.
"People who commit these offenses tend to be predatory and have multiple victims," said Dublin Police Lt. Kurt von Savoye.
There are striking similarities between Michaela's and Jaycee's case both were the same age and had the same appearance when taken and both were snatched off the street.
Police also note the sketch of Michaela's kidnapper matched Garrido's appearance at the time.
Investigators are specifically looking for the clothes Michaela was wearing the day she went missing and any disturbed soil that could indicate a grave site.
"Our aim is to search methodically, systematically and very thoroughly the properties with our own cases in mind," said Hayward Police Lt. Chris Orrey.
"We cannot say the Garridos are with certainty suspects in the case, but we have not been able to eliminate them from the case," said Lt. von Savoye.
On Monday, during the Garridos bail hearing, a judge denied requests from law enforcement agencies to be able to interview both Phillip and his wife Nancy.