Tens of thousands of people took to the streets of Mexico’s capital to mark the passage of 44 years since the October 1968 massacre of student protesters, an anniversary that took on new significance this year with the re-emergence of young people as a force in public life.

The march began in Tlatelolco square, where a few dozen soldiers and paramilitaries opened fire on a peaceful student rally the evening of Oct. 2, 1968.

Efforts to hold anyone in authority accountable have been frustrated by the courts and by Mexican institutions’ persistent unwillingness to hand over information.