The mystery into the disappearance of 43 students in Mexico deepened on Tuesday, when authorities announced that DNA testing on bodies found in a mass grave proved they are not those of the missing men.
The announcement raises questions about the fate of the teacher trainees, who disappeared in late September after clashing with police linked to organized crime in the state of Guerrero.
Authorities have not announced who the dozens of charred remains belong to. Testing on other mass graves in the town of Iguala continues.
Another burial pit was found in the area on Tuesday, as Mexican authorities arrested 14 more police officers accused of abducting the students and handing them over to a gang. At least 36 officers have been held over the disappearances.
Two gang hitmen detained in the case told officials they killed some of the students in collaboration with local police.
Benjamin Mondragon Pereda, the leader of the Guerreros Unidos cartel linked with the Iguala police force and the missing students, fatally shot himself Tuesday after being surrounded by federal police.
Protesters around Mexico have demanded answers from the government, which is under international criticism for human rights abuses committed by security forces. Demonstrations extended into the United States on Tuesday, with dozens of people gathering outside the Mexican consulate in the western city of Los Angeles, California, in frustration over the missing students.