Students take part in a protest in support of the missing students of the Ayotzinapa teachers training college Raul Isidro Burgos, outside the building of the office of Mexico's Attorney General in Mexico City November 6, 2014. The students went missing in the town of Iguala in the south-western state of Guerrero on September 26 after clashing with police and masked men, with dozens of police being arrested in connection with a case that has sent shockwaves across Mexico. REUTERS/Tomas Bravo (MEXICO - Tags: SOCIETY CIVIL UNREST CRIME LAW)