At least some of the 43 Mexican students who disappeared last year under mysterious circumstances were not incinerated at a landfill but killed in a different location in the state of Guerrero, one gang suspect claims in his testimony.

Marco Antonio Rios Berber, a confessed member of the Guerreros Unidos cartel, revealed that 13 students were taken to a hill on the outskirts of Iguala, Guerrero, where at least nine were slaughtered, Agence France-Presse reported based on its analysis of a 54,000-page report published this week by the office of Mexico's attorney general.

"I shot two in the head," and four more were killed by other gang members, Rios said, according to the official documents. A total of six bodies were thrown into a pit, incinerated and covered with dirt and tree branches, he added.

"They left the four others tied up," Rios said. "They had beaten them and left them unconscious."

Attorney General Arely Gómez decided to make the report available after a journalist had sued for its publication under Mexican transparency laws, La Prensa explained.

Tomas Zeron, the government's chief of investigations, suggested that the documents do not contradict the notion that a "large" number of students were incinerated at the landfill. Nevertheless, the official admitted that he could not confirm whether it was all 43.

Frustrated by the twists and turns of the inquiry, meanwhile, the parents of some of the students threatened to impede planned municipal elections in Tixtla, the community of about 20,000 that is home to the Rural Normal School of Ayotzinapa, which their children attended, Noticias 24 noted.

The mother of José Eduardo Bartolo, one of the students whose fate remains unknown, blamed officials for failing to efficiently solve the case that has grabbed international headlines.

"We, the heads of family, will not allow that elections will be held in Tixtla given that authorities from all three branches of government have ignored the issue of returning us our children alive," María de Jesús Tlatempa Bello said.