SAN FRANCISCO — A death row inmate has led authorities to an area of Northern California believed to be the burial sites of two victims of the notorious “Speed Freak Killers,” as searchers focused today on an abandoned well for any additional remains.

A partial human skull and bones were found buried Friday on a remote property in Calaveras County. A day earlier, searchers found a skull and bones at another site in the area about 60 miles south of Sacramento.

They were led there by inmate Wesley Shermantine, who was convicted of murdering 16-year-old Chevelle “Chevy” Wheeler. Authorities say he and childhood friend Loren Herzog killed the girl as part of a methamphetamine-fueled killing spree in the 1980s. The two were arrested in 1999.