Police in San Cristobal say unknown thieves unearthed the remains of Juan Vizcarra Quispe, who died in 1978. His bones were found strewn about the cemetery, but his skull is missing.
Mayor Rogelio Vizcarra says he received a text message offering to return the skull if he withdraws his bid for re-election Oct. 3, but he still plans to run.
San Cristobal police officer Leonardo Castro says authorities are investigating Vizcarra's political opponents.
Castro said Thursday that the theft violates a law against "offending the memory of the dead," punishable by two years in prison.