Forensic experts have identified one of 43 missing Mexican students among charred remains found in a landfill, partly solving a case that has roiled the government for weeks.
Federal authorities sent badly burned remains to an Austrian medical university last month after finding them in a garbage dump and river in the southern state of Guerrero.
"One of the pieces (of bones) belongs to one of the students," a federal official told AFP on condition of anonymity.
Sources close to the families identified the victim as Alexander Mora.
Authorities say the aspiring teachers vanished after gang-linked police attacked their buses in the city of Iguala on September 26, allegedly under orders from the mayor and his wife in a night of terror that left six other people dead.
The police then delivered the 43 young men to members of the Guerreros Unidos drug gang, who told investigators they took them in two trucks to a landfill, killed them, burned their bodies and dumped them in a river.
Despite the confessions, prosecutors have stopped short of declaring the students dead, saying they would wait for DNA test results from Austria's Innsbruck University.
Parents of the students led a new protest in Mexico City on Saturday, the latest in a wave of demonstrations against President Enrique Pena Nieto's handling of the case.
Parents of the missing students have refused to believe their sons are dead, chanting at every protest "they took them alive, we want them back alive".
If all 43 are confirmed killed, it would rank among the worst mass murders in a drug war that has killed more than 80,000 people and left 22,000 others missing since 2006 in Mexico.
The Iguala case has drawn international condemnation, highlighted Mexico's struggle with corruption and undermined Pena Nieto's assurances that his security policy was bearing fruit.
Pena Nieto returned to Guerrero last week for the first time since the students went missing more than two months ago.
