Colombian army soldiers patrol the Loma de Cristo—bal neighborhood after warring gangs forced dozens of families to flee. Medellin used to be the most dangerous city in the world but officials embarked on innovative projects designed to make life better in tough neighborhoods. Paul Smith for NPR hide caption

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Griselda Blanco, the "queen of cocaine," in a 2004 photo posted by the Florida Department of Corrections. Fla. Dept. of Corrections hide caption

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