Police in southern Mexican state of Chiapas have found eight bodies stuffed in plastic garbage bags and dumped on a rural road near Guatemala border, EFE news agency reported on Thursday.
According to provincial Justice Minister Amador Rodriguez Lozano, five bodies were found on Tuesday from a road side in Guadalupe Victoria town and the other three were found in the town of 20 de Noviembre.
Though the victims were yet to be identified, police believe they may include Mexicans, Guatemala or Colombians, he said.
Officials said, the bruise marks on the bodies suggested they were tortured before being killed by shooting to the back of thier head from a close range.
Meanwhile, police in the northern state of Nuevo Leon have also found two burned human heads on a road in the city of Escobedo, the state Attorney General's Office said.
An anonymous caller tipped off authorities to the location of the human remains, the AG's office said, adding that the condition of the heads made it impossible to determine the gender or age of the victims.
On Sunday, the decapitated bodies of eight army soldiers were found along an urban boulevard in the southern state of Guerrero.
Brutal slayings by drug cartels are on the rise in Mexico, and officials estimate that more than 5,300 people have died in organized crime-related slayings this year.
Mexico has been plagued in recent years by drug-related violence, with powerful cartels battling each other and the security forces, as rival gangs vie for control of lucrative smuggling and distribution routes.
Armed groups linked to Mexico's drug cartels murdered around 2,700 people in 2007 and 1,500 in 2006, with the death toll this year already at more than 5,300, according to governemnt data.