The prospect of continuing street violence before the two milestone events on the national calendar looms as government forces battle to control organized crime's rule over Rio's vast slums, and increased bloodletting in gang wars in Brazil's business heartland and Latin America's largest city, Sao Paulo.
A military-led "pacification" program targeting organized crime's grip over Rio's favelas began soon after the transfer of the Olympics mantle to Brazil at the end of the London Olympics in July.
Tough new measures to displace criminals from the slums got mixed reactions from public representatives and the media but were widely welcomed in Brazil.
What few expected was the explosion of gun violence in Sao Paulo, oversimplified in media reports as the gangs' war on the city's law enforcement agencies.
Critics say the gangs' violence is a response to the police use of excessive force and warn that a similar crisis threatens Rio de Janeiro, venue for both the World Cup and the Olympics.
Dozens have been killed and scores wounded in Sao Paulo. Reliable data from police action against organized crime in Rio remain scarce.
Academics and independent researchers have warned Brazil's formidable organized crime network is on a warpath and is targeting symbols of the state. Police are high on its target list.
More than 100 police personnel have been killed, at least 40 of them identified clearly as victims of summary executions.
The new mayor of Sao Paulo, Fernando Haddad, represents President Dilma Rousseff's ruling Workers Party.
Concern over the impact of the violence on the World Cup and Olympics has mounted as independent data show police executions of suspects have mounted with the new emphasis on cleaning up Brazil's image before the two sport events.
Police and prosecutors' offices say Brazil's law enforcement and prison system faces paralysis amid indications that increasing numbers of inmates are already members of prison gangs, particularly a powerful criminal organization, Primeiro Comando da Capital, or First Command of the Capital.
The PCC became active in 1993 but has increasingly evolved into a lethal anti-establishment body sworn to destabilizing the justice system in Brazil.
Critics say Brazil's law enforcement agencies have helped the PCC's rise with their own illegal practice of delivering justice to those they suspect of wrongdoing.
Rousseff's administration pledged additional federal aid, including increased intelligence and drug-combating operations, but occasional shutdowns of neighborhoods, including schools, are commonplace.
Rousseff is keen to reverse the country's crime trend that still rates Brazil as one of the world's most violent counties. The average homicide rate in Brazil over the past decade has remained around 26 per 100,000 inhabitants.
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