Police say Lenin Carballido's family produced a death certificate in his name in 2010, when he was under investigation for a gang rape.
His party, the leftist Democratic Revolution Party (PRD), said it had been fooled by Carballido, and that would not be allowed to serve as mayor.
"When he registered as a candidate, he presented all his paperwork, his birth certificate, a letter stating he had no criminal record," said Rey Morales of the PRD. "He fooled the prosecutors' office, he fooled the office of records, he fooled electoral officials."
The death certificate, signed by a doctor and issued by the local records office, listed Carballido's cause of death as "natural causes" following a diabetic coma.
Carballido now faces allegations of voting law infringements, and prosecutors are investigating whether he faked his death. Authorities say they may also reopen the gang rape investigation Carballido avoided.