Ten complete bodies, three headless bodies and four severed heads were found when authorities dug up a pit in a house in the Mexican state of Durango, authorities said Friday.
Authorities are determining whether some of the heads belonged to the bodies. The badly decayed corpses _ which have not yet been identified _ were taken to a morgue for autopsies, the Durango state prosecutor's office said in a statement.
Durango has been the scene of a bloody turf battle between the Sinaloa Cartel and the Zetas gang. The grisly discovery comes as mass graves with dozens of bodies have been discovered in the northern state of Tamaulipas, where the Zetas are fighting the Gulf Cartel.
Also Friday, Mexico's army announced that it had captured a man who allegedly confessed to participating in the killing of a well-known poet's son and six other people.
The March 28 slaying of Juan Francisco Sicilia, the son of poet Javier Sicilia, sparked demonstrations throughout the country against the violence of Mexico's drug war, which has claimed more than 34,000 lives.
But the circumstances of the arrest in the high-profile case immediately drew suspicions.
The army said suspect Rodrigo Elizalde Mora was captured Thursday in the central city of Cuernavaca, where the killings occurred.
He confessed to working for the South Pacific Cartel, led by reputed drug lord Hector Beltran Leyva, and to helping kill Sicilia and a group of friends, according to the army statement.
But Elizalde Mora appeared before reporters badly beaten, and said he had been kidnapped by four unidentified men in a sport utility vehicle, who then apparently turned him over to authorities.
"They picked me up and they beat me," Elizalde Mora told local media.
After Sicilia's killing, several mysterious banners were hung around Cuernavaca vowing that the perpetrators would be hunted down and punished. The crime had initially been blamed on the Gulf cartel, but the new banners said the South Pacific cartel was responsible.
The chain of events was similar to what happened in 2008, when three suspects were quickly arrested for a grenade attack on a crowd celebrating Mexico's independence that killed eight people.
The suspects say they were kidnapped, apparently by a drug cartel, beaten and left for authorities.
Julio Hernandez Barros, the lawyer for Sicilia's father _ who has been pushing for justice in his son's case _ said Elizalde Mora's confession was dubious. The suspect said Sicilia had been killed by a South Pacific Cartel gunmen after they got in a dispute because of an insult to a woman at a restaurant.
Hernandez said there was no evidence of any such run-in, adding that Elizalde Mora mentioned the wrong restaurant and the wrong times in his confession.
"There are some things that do not match the facts," Hernandez Barros said. "I think there are people who are interested in distorting the investigation."
"I think that even the authorities don't trust it," he said of the confession, though he conceded that a drug cartel may have been responsible for the killings.
The Gulf Cartel has been locked in a bloody turf battle with the South Pacific _ a remnant of the Beltran Leyva cartel _ in Cuernavaca, just south of Mexico City.