FBI is in Calaveras County to investigate a murder that may have occurred many years ago.
Search crews, including dogs from Santa Clara County, unearthed a human skull in rural Calaveras County.
The find is not believed to be connected to the Michaela Garecht missing child case out of Hayward even though the same killer made claims about Michaela. The Michaela claim did not include any mention of her remains.
In a letter to a Stockton newspaper, Wesley Shermantine linked his partner in crime Loren Herzog to the 1988 disappearance of the Hayward child, saying that Herzog looked a lot like the sketch of the little girl's kidnapper.
In separate claims made to a bounty hunter, Shermantine gave directions to the location of bodies of other victims. That is where the remains were found.
Shermantine claimed the two "partners in crime" buried a number of bodies in San Joaquin and Calaveras County. He said they were buried on a property once owned by his family. That is the same property where the skull was discovered Thursday.
Initial reports said that the skull found this week is believed to be that of 25-year-old Cyndi Vanderheiden who disappeared in 1998.
Herzog committed suicide last month after serving time for the killing of Vanderheiden.
But Shermantine's claim was that there was more than one body buried on the property.
Shermantine has been in prison for more than a decade after being convicted of multiple murders while he was part of an infamous crime team that included Herzog, known as the "Speed Freak Killers." The men are suspected of killing more than 20 people during a drug-fueled rampage in the 1980s and '90s that ended when they were arrested in 1999, authorities said.
Below is a prison photo of Herzog and the sketch from the Michaela Garecht kidnapping case. Hayward police are aware of the claims and said they will talk to Shermantine once the search for bodies is complete.