Rio de Janeiro state promised improvements in public security in preparation for the Olympics, but it has not done enough to address extrajudicial executions by police, a central obstacle to more effective law enforcement. Unlawful police killings have contributed to the unraveling of the state’s ambitious efforts to improve public security. Rio police have killed more than 8,000 people in the past decade, including at least 645 in 2015. Many police killings were most likely the result of the legitimate use of force, but many others were extrajudicial executions.