The parents of Mexican students believed murdered by a drugs gang appealed to the United Nations on Monday for help in seeking justice, saying they had no faith in the government's ability to investigate the crime.
President Enrique Pena Nieto's government said last week that the 43 trainee teachers who disappeared four months ago were killed on the orders of a drug cartel who mistook them for members of a rival gang.
The killings, which shocked a nation already suffering from endemic crime-related bloodshed, have led to mass protests against the government and fueled the widely held belief that organized crime and certain politicians have close links.
"We've decided to come here, to this committee, to get some support and to really obtain justice, given the fact that our government is not able to do anything," Bernabe Abrajan, whose son Adan was one of the victims, told reporters on the sidelines of a U.N. Committee on Enforced Disappearances session.
He was wearing a T-shirt bearing a photo of his son. The session began with a minute of silence for the victims.
Mexico's attorney general has said that the students' bodies were incinerated and thrown into a river. The remains of only one has been identified so far. The mayor of the town of Iguala and his wife have been arrested as two chief suspects.
The committee pressed repeatedly about the scope of investigations, the national data base on missing persons, and protection programmes for witnesses and complainants.
Committee member Juan Jose Lopez Ortega asked: "How many public officials have been removed from public office in connection with investigations under way?"
Juan Manuel Gomez Robledo, a senior Mexican foreign ministry official and head of the government delegation, said the disappearance of the students showed the need to make a stand against organized crime as well as addressing problems linked to poverty and corruption.
Amnesty International said it had documented cases of abductions and disappearances when Mexican security forces, including the army, had supported or turned a blind eye to the work of criminal gangs.
The U.N. committee oversees compliance with a treaty banning enforced disappearances through arrest or abduction by state agents or people working with the backing of the state.