That weekend began like so many others in the southern Mexico town: The main square hosted a political rally and there was a soccer match nearby. Students from a rural teacher-training college were trying to secure buses for a trip to Mexico City.

But what happened on that Friday, Sept. 26, 2014, has become a symbol of the violence, impunity and broken rule of law that plagues Mexico. By the end of the night, six people were dead, and 43 of the students, last spotted being forced into police trucks, had vanished. Five years on, their whereabouts are still unknown, their cases unsolved.

They are now among the more than 40,000 other people in Mexico who are registered as disappeared, many in the country’s drug war.

This much is known: In one violent and chaotic night, local police officers, working with a criminal gang and the mayor, stopped and shot at the buses carrying the teacher-training students. Later, they fired at others also on their way out of town — taxis, and the soccer team’s bus — though they were not connected to the students. There is still no information about what exactly happened, why, who was involved or even where the students are.