Further forensic tests of the soil at the remote ranch where Charles Manson once lived were ordered Friday before a decision is made on whether to dig for more possible victims of the convicted killer.
"Barker Ranch is national park property," Inyo County Sheriff Bill Lutze said in a statement, explaining that its location is a compelling reason "to be as cautious as possible and use every reasonable testing method available before disturbing the ground with excavation."
The decrepit ranch is within the boundaries of Death Valley National Park, in the rugged Panamint Mountain range. Manson and his followers retreated there after a 1969 killing spree that set Los Angeles on edge.
Manson is serving a life sentence at Corcoran State Prison for the murders of seven people, including actress Sharon Tate.
Last month, a team of researchers from Tennessee's Oak Ridge National Laboratory conducted tests of the soil at the site using new forensic technology. The team's equipment looked for chemical markers that match those released during decomposition of human bodies.
Results from that first search, which focused on surface soil samples, showed that there could be at least two unmarked graves at the ranch. But Lutze, the law enforcement official with jurisdiction of the area, called for a second trip that would likely examine deeper soil samples.
The date of the second set of tests is still uncertain, Lutze said.
In search of clandestine graves
It's still unclear whether the researchers from the national lab will return to the ranch themselves, or whether law enforcement officials will gather samples that can be analyzed in the Tennessee lab, said Arpad Vass, senior researcher at Oak Ridge.
Vass was part of the team that visited Barker Ranch last month in search of possible clandestine graves at the cult's last dwelling. He spent years building a database of decomposition odors that can help them determine how long a body has been in the ground — technology he hopes will eventually be used to help law enforcement find unknown graves.
In further testing, investigators likely would try to develop the site's depth profile, taking core samples of the soil to see if the presence of certain compounds increases further down, Vass said.
A decision about whether to dig will be made after results from the second round of testing are revealed, likely in late April, Lutze said.