In Mexico City on Wednesday, people march to demand justice for 43 missing students. Mexican authorities ordered the arrest of the mayor of Iguala and his wife in connection with the attack. Yuri Cortez/AFP/Getty Images hide caption

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Students chant slogans in front of the Attorney General Office in Mexico City on Wednesday during a protest over the 43 students missing in Iguala, Guerrero State. Omar Torres/AFP/Getty Images hide caption

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Groups of rural and community police arrive in the city of Iguala on Tuesday to help in the search for 43 students who disappeared after a confrontation with local police on Sept. 26. Miguel Tovar/STF/LatinContent/Getty Images hide caption

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Nicaraguan President Daniel Ortega celebrates with first lady Rosario Murillo a day before his re-inauguration in 2012. Rodrigo Arangua/AFP/Getty Images hide caption

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Migrants at a shelter in southern Mexico say that Mexico's interior checkpoints are making it harder to travel north. Some have given up on reaching the U.S. and are trying to stay in Mexico. Carrie Kahn/NPR hide caption

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A man looks out towards the US from the Mexican side of the border fence that divides the two countries in San Diego. The U.S. Border Patrol says it has seen about a 60 percent drop in the number of Central Americans apprehended at the border. Mark Ralston/AFP/Getty Images hide caption

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