Mexico marked one month since the disappearance of 43 students in the state of Guerrero with another round of arrests, but no less mystery as to the whereabouts of the young men.
The country's Attorney General, Jesus Murillo, said Monday four more gang members from the Guerreros Unidos cartel who "organized the disappearance" of the teacher trainees from the town of Iguala in late September were in custody.
There has been speculation of a massacre, and nearly 60 police officers and gang members have been arrested.
But there has been no sign of the students after they clashed with police under mysterious circumstances last month.
Initial DNA testing showed that charred bodies found in communal graves in Iguala are not the students.
However, Mexican media reported Monday that the military was guarding the perimeter of a newly discovered gravesite near Iguala.
Six people were killed at the scene and dozens were wounded the night of September 26, after police and armed civilians opened fire on three buses filled with students.
Authorities allege Iguala's fugitive mayor, Jose Luis Abarca, ordered the attack to prevent the students from disturbing an event held by his wife.
Guerrero's new interim governor, Rogelio Ortega, said Monday, "Our priority is to find the 43 students from the Ayotzinapa school alive."
He replaced the previous governor, Angel Aguirre, who resigned last week amid the growing scandal over the missing students.
Protesters around Mexico continued to demand answers from the government, which is under international criticism for years of human rights abuses committed by security forces, including kidnappings and extrajudicial killings.