Panamint Springs, Calif. ? A day’s work in 100-degree heat at a remote ranch once used as a hangout for the notorious Charles Manson family yielded only a .38-caliber shell casing Tuesday.

But a posse of Inyo County sheriff’s investigators was expected to continue the dig in Death Valley National Park.

Armed with ground-penetrating radar, spades and a cadaver dog named Buster, the mission of the 20-member group was to wring every fact out of the sandy soil at the ranch where Manson and his followers holed up in 1969 after the massacre of pregnant actress Sharon Tate and six others.

Of particular interest Tuesday were two sites where cadaver dogs and analyses of soil samples produced mixed but somewhat encouraging results that could support lingering rumors that bodies might be buried at Barker Ranch. The collection of sheds and a rock-and-plaster ranch house are five miles up a rugged black rock canyon at the park’s southwestern boundary.

Inyo County Sheriff Bill Lutze has said five sites might be excavated over the next few days amid temperatures forecast to hover near 110 degrees.

Manson directed the gruesome forays that resulted in the massacre of Tate, three friends and a teenager at her Los Angeles home and the slaying of a couple the next night.

A member of the Manson family later suggested that there were bodies buried at Barker Ranch.

The ongoing investigation has involved forensics experts from the Utah attorney general’s office, the private laboratory Evident Inc. of Virginia, an archaeologist from California State University, Long Beach, and members of the Anthropology Research Facility at the University of Tennessee in Knoxville, otherwise known as the “Body Farm.”

Locals predicted that investigators might unearth ancient Indian graves. Some park rangers speculated that if human remains are discovered at the ranch, they might be connected to a separate Death Valley mystery: the 1996 disappearance of four German tourists – architect Egbert Rimkus, 34, his girlfriend, Cornelia Meyer, 28, his 10-year-old son Georg Weber, and Meyer’s son Max, 4.