Some three thousand people took to the streets of downtown Mexico City on Friday, three months after the disappearance and likely massacre of 43 students.
The students went missing on September 26, in an apparent massacre by a police-backed gang that sparked nationwide protests and caused a crisis for President Enrique Pena Nieto.
The latest marches in Mexico City were led by parents and other relatives and friends of the missing, including students from their teacher training college in southern Guerrero state.
"We want them alive," protesters chanted, walking behind gigantic portraits of the missing students and a huge Mexican flag whose red and green colors were replaced by black.
"What does Ayotzinapa want?" protest leaders called out, referring to the name of the students' school. "Justice! Justice!" the crowd responded.
If all the students are confirmed dead, 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.
Authorities say the aspiring teachers vanished after gang-linked police attacked their buses in the city of Iguala, 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 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.
For now, only one of the students has been positively identified from charred remains, which leaves little hope of finding the 42 others.
On Christmas Eve, the students' parents had already protested under heavy rains in front of the Los Pinos presidential palace.
And in a sign of the violence that continues to reign in Guerrero state, the body of a priest was found with a bullet wound to the head.
Gregorio Lopez Gorostieta was discovered in the Tierra Caliente region two months after another priest's body was found.