A decade after their children vanished, the parents of 43 Mexican students, presumed to have been massacred, gather with demonstrators outside the Interior Ministry in the capital to demand justice. "Three days before the 10th anniversary, we remain steadfast, convinced of finding our children," says Maria Elena Guerrero, mother of one of the disappeared students. The case of the students from the Ayotzinapa teacher training college in the southern state of Guerrero is considered one of the worst human rights atrocities in Mexico, where a spiral of drug-related violence has left more than 100,000 people missing. IMAGES AND SOUNDBITES