Inyo County Sheriff Bill Lutze issued a statement Friday saying an earlier search of Barker Ranch, located in Death Valley 150 miles west of Las Vegas, utilizing a cadaver dog and detection equipment was inconclusive, the Las Vegas Review-Journal reported Saturday.

"There was no consistent response from the dogs that searched, and no conclusive findings from the soil samplings tested by top experts in the field," Lutze said. "Therefore, I believe the only way to determine once and for all whether there are bodies buried at Barker Ranch from the time of the Manson family is to proceed with limited excavation in a very few areas."

Authorities are to begin about four days of digging on May 20, the newspaper reported.

Manson, now 73 and serving a life sentence in a California prison, and his followers wound up at Barker Ranch and nearby Myers Ranch after a series of slayings in Los Angeles, including the killing of actress Sharon Tate. There have been rumors for years that other Manson family victims are buried on the Barker property.