The parents of 43 students missing in Mexico have led a march of thousands of people in the capital to mark one year since their disappearance, the BBC reported on Sunday.
Many carried photos of their loved ones in Mexico City, demanding justice.
The parents want the government to hand over the investigation to a special unit under international supervision.
They dispute the government's account that the students were handed over by police in the city of Iguala to a criminal gang, which killed them.
A group of independent experts has suggested the students were killed because they unknowingly took control of a bus carrying illegal drugs, and the government did nothing to protect them.
Meanwhile, President Enrique Pena Nieto has announced the creation of a special team to look into the case.