Police in Mexico say they have found at least 19 bodies in an abandoned mine shaft in Hidalgo, near Mexico City.
The security forces said they found the decomposing remains after a tip-off from two alleged members of a drug cartel they had arrested on Friday.
The two men also named nine police officers who they say worked for their cartel, Los Zetas.
The nine have been arrested and are being questioned, while police continue to search the area for more bodies.
They say the two alleged cartel members told them there were more human remains at at least four other locations in the area.
“There are indications that the bodies found may be those of drug dealers,” Hidalgo Deputy Attorney General Maria del Carmen Archundia told reporters.
The bodies were in an advanced state of decomposition, making it impossible to identify the victims, Archundia said.
Tissue samples will be sent to the genetic laboratory of the Attorney General’s Office, she said.
Four of the bodies were found inside the entrance of a mine in the city of Mineral del Chico, while others were discovered at a mine in El Castillo, a neighborhood in the city of Pachuca.
The second group of bodies was found after a shootout between police and a gang of suspected kidnappers.
Three of the kidnappers, including a minor and a municipal police officer, were arrested.
The suspects told officers they had dumped the bodies at the mine’s entrance.
The bodies had been at the mine for at least 18 months, an AG’s office spokesman said.
The gang had the backing of two municipal police officers, both of whom have been arrested.
Mexico’s drug cartels often get rid of the bodies of slain enemies and kidnapping victims in mines.
The bodies of 55 people were found earlier this summer at an abandoned silver mine in Taxco, a city in southern Mexico.
The bodies were found in an air shaft at the San Francisco de Cuadra mine in Taxco, a city located 187 kilometers (116 miles) south of Mexico City.
The mass grave was discovered on May 29.
About 28,000 people have died in drug-related violence since President Felipe Calderon declared war on Mexico’s cartels shortly after taking office in December 2006.
More than 7,000 gangland killings have occurred so far this year in Mexico, officials said.
The death toll for all of 2009 was 7,724.