Mexico missing: Thousands march to demand full investigation
Thousands of people have taken part in demonstrations in Mexico City to demand a full investigation into the disappearance of 43 students four months ago.
The trainee teachers went missing after taking part in a protest in the south-western town of Iguala on 26 September.
Prosecutors say they were seized by local police and handed over to a local gang, which killed them.
Those marching included the families of the missing students.
They started their journey from four different suburbs of Mexico City and headed to the city's main square, the Zocalo.
More than 100,000 people have been killed or have disappeared in Mexico.
But the BBC's Katy Watson in Mexico City says the case of the 43 students has galvanised Mexicans angry with high levels of corruption and collusion between local authorities, police and criminal gangs.
'Carry on fighting'
Relatives of the 43 trainee teachers are sceptical about the official version of their disappearance.
"We will carry on fighting until we find them, until the end," Macedonia Torres, the mother of one the missing students, told Grupo Formula radio.
"I don't believe they are dead. And if they are dead we will hold the government responsible," added Maximino Hernandez, father of Carlos Lorenzo Hernandez.
At the scene: BBC's Katy Watson in Mexico City
Tens of thousands of protestors marched to the capital's main square, many carrying pictures of the missing, waving blood-stained flags or posters saying "They were taken alive, we want them back alive now".
But in a country used to headlines of violence, the "mega-march" was largely peaceful.
Parents of the missing took turns to speak, calling for justice and for the government to do more to find out what happened to the missing students.
There is little faith, though, that the authorities will bring the perpetrators to justice.
Prosecutors say members of the gang confessed to killing the 43 and burning their bodies after they were told the students belonged to a rival gang.
But the remains of only one student, Alexander Mora, have been identified so far, after being taken for DNA tests at a forensic centre in Austria.
He was in his first year of studies at the rural teacher training college in Ayotzinapa, a college with a tradition of left-wing political activism.
Alexander Mora was part of a group of students who travelled to nearby Iguala on 26 September and, as part of a protest, commandeered a number of buses.
On their way back to their college the students were intercepted by police allegedly on the orders of the local mayor, who wanted to prevent them from disrupting a speech his wife was giving at a public event that evening.