LINDEN (AP) — A convicted California serial killer whose maps led authorities to at least three burial locations, including an abandoned well holding hundreds of human bone fragments, has revealed the site of another well where more remains could be found, according to a bounty hunter working on the case.

Death row inmate Wesley Shermantine began disclosing where victims were buried after bounty hunter Leonard Padilla offered him money for the information.

The biggest find so far came in an old well near the San Joaquin County town of Linden, where Shermantine said 10 bodies or more could have been stashed. Searchers found about 1,000 human bone pieces, which are being analyzed for possible identification.

Searchers, led by the Sheriff's Department, are currently looking for a second well in the area that could hold more remains.

Meanwhile, Shermantine described the location of a third well in a phone conversation Monday night with Padilla, the bounty hunter told the Sacramento Bee.

"It means that there's another body out there to be found," Padilla said.

All three wells are about a mile apart in an area where Shermantine and childhood friend Loren Herzog were raised. Known as the "Speed Freak Killers," the pair went on a methamphetamine-fueled killing spree in the 1980s and 90s, possibly murdering dozens of people before their 1999 arrests, authorities said.

Shermantine was convicted of four murders and sentenced to death. Jurors found Herzog guilty of three murders, but those convictions were later overturned after a judge determined his confession was illegally coerced. He instead struck a plea deal on one count of voluntary manslaughter and was paroled in 2010.

Herzog died in an apparent suicide last month, hours after receiving a call from Padilla to warn him that Shermantine planned to reveal the burial locations.

Using maps roughly drawn by Shermantine from his San Quentin State Prison cell, authorities first searched a remote Calaveras County property once owned by his family and found two sets of human remains. Tests preliminarily confirmed they belong to Cyndi Vanderheiden, 25, who disappeared in 1998, and Chevelle "Chevy" Wheeler, 16, who disappeared in 1985.

Shermantine was convicted of both murders in 2001, and Herzog's voluntary manslaughter plea was for Vanderheiden's death.