Authorities have found five decapitated bodies in western Mexico, with letters left with the corpses purportedly signed by a drug cartel, officials have said.
The bodies, with their heads laying nearby, were found shortly before dawn on Saturday in two different locations in Michoacan state, a region struggling with gang turf wars.
Three of the corpses were found on display on a bridge's traffic circle in Tarimbaro, a suburb of Morelia, the state's capital, said Michoacan chief prosecutor Marco Vinicio Aguilera.
"A knife that may have been used to cut the heads was found in the area," he told the AFP news agency.
About an hour later, two more were found in a Morelia public square, with the heads on a pavement a little further away, Aguilera said.
A letter signed with the initials of the Jalisco New Generation drug cartel were found with all the bodies.
The gang, which operates in the neighbouring state of Jalisco, is engaged in a heated turf battle with the Knights Templar cartel, which has dominated Michoacan's drug trade in recent years.
Michoacan's murder rate rose in 2013 compared to declines in most states.
Last month, dozens of mutilated corpses were found buried in mass graves in an area on the border between the states of Michoacan and Jalisco.
The extortion and murders committed by the Knights Templar prompted several towns to form vigilante armed groups in February.
Authorities say some of the self-styled "self-defense" units are supported by the Jalisco drug cartel, a charge the vigilantes deny.
The federal government deployed thousands of troops to Michoacan in May to crack down on the cartels, but gruesome acts of violence have continued.
Just last week, three local police officers were assassinated in the span of two days.
Decapitations became an increasingly common form of gangland vengeance across Mexico since five heads were tossed onto a barroom dance floor in the Michoacan town of Uruapan in 2006.