The parents of 43 missing students began a protest tour of Mexico, rejecting claims their sons were slaughtered in a crime rattling the nation and its leaders.
Hundreds of people marched in support as a convoy of buses left with families and dozens of fellow students in Ayotzinapa, home of the missing young men's leftwing teacher-training college in the southern state of Guerrero.
The parents, who deeply distrust the government, want to tell fellow Mexicans that they do not believe their sons are dead and that the authorities should find them alive.
Violent protests have erupted since officials announced last week that Guerreros Unidos drug gang henchmen confessed to murdering the students and incinerating their bodies after receiving them from corrupt police in September.The government has stopped short of declaring them dead, saying it would wait for DNA results of remains that were sent to forensic specialists at Austria's University of Innsbruck late Wednesday.
Federal police and some relatives are still combing the region for the students.
"They have disappeared but they are not dead. We want help finding them," said Blanca Navas, mother of missing student Jorge. "I don't believe the government at all. They've only been saying pure lies."
Carrying food and posters of their children's faces, parents boarded a first group of three buses that headed north to Chihuahua state, which borders the United States and has endured gruesome drug violence that has plagued Mexico for years.Others were heading to the impoverished southern state of Chiapas. The convoys plan to converge in Mexico City next week.
"There is no doubt that the nightmare our sons went through was committed by the state. It confirms the collusion between the authorities and organized crime," families spokesman Felipe de la Cruz told AFP before hopping on a bus.
"They took them alive, we want them back alive," hundreds of people chanted as the buses left, repeating a mantra shouted at every protest.
- US calls for calm -The crime has turned attention away from President Enrique Pena Nieto's internationally acclaimed economic reforms and undermined his assurances that his national security strategy was bearing fruit.
Pena Nieto was heading to the G20 summit in Australia after meetings in China this week, brushing aside critics who said he should have stayed home to deal with the growing unrest.
"He didn't care about our suffering," said one of the missing student's father, Epifanio Alvarez.
Last weekend, thousands of people protested in Mexico City and a small group set fire to the door of the historic National Palace. Others have rallied in the states of Oaxaca and Michoacan.
But the biggest shows of anger have been in Guerrero, where protesters burned the state legislature and the regional headquarters of Pena Nieto's Institutional Revolutionary Party (PRI) this week.
The US State Department appealed for calm and a transparent investigation into the "heinous and barbaric crime."
The US embassy sent an emergency message saying US government employees were prohibited from traveling by land in Guerrero due to the protests. It cautioned other American citizens to "avoid virtually all road travel" in the state.
Tourism officials have pleaded for a stop to violent protests which have led to lower-than-usual hotel reservations in Guerrero's Acapulco beach resort.
- Parents await DNA tests -
Parents of the students say they will only believe their sons are dead when they get DNA results from independent international experts.
The students vanished on September 26 after police shot at their buses in the city of Iguala, killing six people, and delivered the 43 to the Guerreros Unidos drug gang, authorities say.
The young men had traveled to collect funds but also stole four buses to return home when they came under fire.
Prosecutors say the city's mayor ordered police to confront the students over fears they would disrupt a speech by his wife.