Police in Rio launched a major operation early on Sunday to wrest control from criminals of the Rocinha favela, or shantytown, the largest in Brazil. The shantytown has been controlled by narcotraffickers for the past 30 years. Rio has one of the highest murder rates in the country and the crackdown on Rocinha drug gangs is part of an official campaign since 2008 to restore security in the city before the 2014 World Cup and the 2016 Summer Olympics, which Brazil will host. Rocinha, built on a steep hillside overlooking the "Marvelous City" and located between two wealthy neighborhoods, would thus become the 19th favela to be cleared of traffickers. Endemic and chronic urban violence has long tarnished the image of Rio, where more than 1.5 million people live in 1,000 slums spread throughout the city. Antonio Bonfim Lopes -- also known as "Nem" and considered one of Rio's most wanted criminals -- was caught in the area last week as police tightened their noose ahead of the assault on Rocinha.