Nearly 40 years have passed since actress Sharon Tate and eight others were savagely murdered by Charles Manson's "Family"—a cult of hippies—but the case is far from closed. While Manson, now 73, serves out his life sentence at Corcoran State Prison in California for the killings, authorities will begin excavating at the Barker Ranch in Death Valley on May 20 in an effort to see if there are more victims of the Family buried there. "There are people missing who were last seen there," says Emmett Harder, 76, a gold prospector in the area who got to know Manson and his followers when they hung out at the ranch in the '60s.

Ten years ago another dig at the Barker ranch, where Manson was captured in 1969, yielded no results. The current excavation, at different sites, stems mostly from the efforts of police Sgt. Paul Dostie, of Mammoth Lakes, Calif., and his cadaver-sniffing black Labrador, Buster. Intrigued with the case and the rumors that have swirled about possible other victims, Dostie trained 4-year-old Buster to detect decomposing bone, not just flesh—a relatively new canine science. A February 2007 search of the ranch by Buster and other dogs highlighted several potential graves. Says Debra Tate, the sister of Sharon: "Buster is outrageously talented."

Aside from curiosity, is there any practical benefit to the excavation? Manson prosecutor Vincent Bugliosi points out that if Manson could be convicted of new murders, he could face the death penalty. "I hate to say it," says Bugliosi, but until now, "in a way Manson has beaten the rap."