Suspected members of the Los Caballeros Templarios (Knights Templar) crime outfit killed and decapitated five men in the pre-dawn hours of Saturday in the southwestern Mexican state of Michoacan, officials said.
Three of the bodies were dumped in Tarimbaro, a town north of the state capital of Morelia, shortly before 6:00 a.m., the state Attorney General's Office said.
The bodies had been placed on a bridge near the upscale Erandeni residential complex.
The three heads had been left next to the bodies, along with a message in which the Caballeros accused the victims of belonging to a drug gang from the neighboring state of Jalisco.
Two other bodies were found shortly afterward in the main square of Tenencia Morelos, part of the municipality of Morelia.
Authorities found the heads next to the bodies along with a similar threatening message, officials said.
Police are investigating the five murders and still working to identify the victims, the state AG's office said.
On Monday, suspected cartel henchmen killed the police chief of the town of Tarimbaro, Michoacan, Luis Manuel Gonzalez Magaña, and his deputy, Osvaldo Rendon Mendoza.
Roberto Carlos Vidales, a politician and local leader of the center-left Party of the Democratic Revolution, or PRD, in Michoacan, was killed inside his car that same day.
The Caballeros, a gang that originated in December 2010 as a faction of the La Familia Michoacana criminal organization, operates in Michoacan and uses its more than 270-kilometer (170-mile) Pacific coastline to smuggle in synthetic-drug precursor chemicals from Asia.
The gang also uses the state's remote mountainous, wooded and arid regions to set up laboratories for making crystal meth for subsequent shipment to the United States, the world's largest market for illegal drugs.
Community self-defense groups, which first emerged on Feb. 24, 2013, to combat the Caballeros, now operate in 13 of Michoacan's 113 municipalities
Members of those groups accuse drug traffickers of carrying out crimes such as kidnappings, murders and robberies, running extortion networks, and committing sexual abuses.
Self-defense groups currently operate in the Michoacan municipalities of Buenavista Tomatlan, Coalcoman, Aguililla, Tepalcatepec, Los Reyes, Chinicuila, Aquila, Paracho, Cheran, La Huacana, Tancitaro, Churumuco and one community in Apatzingan. EFE