Mexican President Enrique Pena Nieto said on Thursday that he has met the families of 43 students who went missing in late September, and pledged results in the case.
"At a meeting that lasted almost five hours, I listened attentively to the demands and concerns of the families of the students," Pena Nieto said on its Twitter account.
On Wednesday, the parents and other family members arrived at the presidential palace of Los Pinos, in the capital Mexico City, aboard three buses accompanied by a police escort.
During the meeting, media reported, parents demanded authorities modify their line of investigation, which has focused on locating mass graves in and around the town where the abductions occurred, and digging up the bodies buried there. To date, more than 30 bodies have been recovered from more than 20 graves.
"They were taken alive and we want them back alive" has turned into a grim rallying cry adopted not just by the parents, but also national and international civic and human rights organizations that have taken up the students' cause.
The meeting ended with Pena Nieto and the families of the victims signing a 10-point document outlining government action in the case, including expanding the search and rescue efforts, recognizing the students as victims and not delinquents, as officials originally indicated, and providing medical attention for students injured in the attack.
"The investigations will be thorough. We will continue to speak with transparency and to seek the truth behind the incidents," the president said.
Several parents were critical of the meeting, telling a radio news broadcast Thursday they were "expecting something more effective."
Emiliano Navarrete, whose 18-year-old son is among the students abducted, said he told Pena Nieto: "I haven't come to ask you for a favor, I've come to ask you for justice."
The perpetrators, he added, "were government people who committed a crime against our boys."
The students, from a rural teachers college, went missing on Sept. 26 following a clash with police linked with drug gang members in the city of Iguala, which along with Acapulco is located in Mexico's violence-torn southern state of Guerrero.
The disappearance of the students have shocked Mexico and sparked nationwide demonstrations.