The dead included two minors, state prosecutors said. All were male and most had been shot in the head and bore signs of torture (link in Spanish). Hand-scrawled threatening messages that were left with the bodies alluded to the fight between rival drug cartels.
Michoacan has been the scene of intense warfare between the state's once-dominant La Familia gang and a rival offshoot calling itself the Knights Templar. The state is also the first place President Felipe Calderon deployed troops when he launched his offensive against traffickers at the start of his administration five years ago. Michoacan is Calderon's home state and recently saw regional elections badly marred by traffickers' threats.
"We are once again news today, nationally and internationally, because of this macabre event," Zitacuaro Mayor Juan Carlos Campos Ponce told reporters (link in Spanish).
In more peaceful times, Zitacuaro was a jumping-off point for tourists observing the famous monarch butterflies who migrate to the region this time of year.
-- Tracy Wilkinson
Photo: Blankets cover some of the 13 corpses discovered Monday near a gas station in Zitacuaro in Mexico's Michoacan state. Credit: Agencia Quadratin / Agence France-Presse / Getty Images