New York Police Department Commissioner William Bratton attends a press conference after witnessing police being retrained under new guidelines at the Police Academy on Dec. 4. Andrew Burton/Getty Images hide caption

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New York City Police Commissioner Bill Bratton speaks during an NYPD swearing-in ceremony in New York on Jan. 7. He confirmed to NPR today that there had been a work slowdown by officers in the weeks since two police officers were shot dead. He said the matter was being corrected. Seth Wenig/AP hide caption

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New York City police officers march before funeral services for police officer Wenjian Liu at Aievoli Funeral Home, in Brooklyn on Sunday. Liu and his partner were gunned down in an unprovoked attack on Dec. 20. Julio Cortez/AP hide caption

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Vice President Joe Biden, center, arrives for funeral services for New York City police officer Rafael Ramos at Christ Tabernacle Church, in the Glendale section of Queens, on Saturday. Julio Cortez/AP hide caption

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Protesters march through Midtown Manhattan on Tuesday, a day after New York City's mayor called for a pause in the demonstrations. Michael Graae/Getty Images hide caption

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New York Police Department Chief of Detectives Robert Boyce said Sunday that a gunman told bystanders to follow him on Instagram, then shot and killed two police officers in Brooklyn on Saturday. Stephanie Keith/Reuters/Landov hide caption

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In this frame grab taken from video provided by the New York Police Department, an unidentified man approaches New York City police officers with a hatchet Thursday. The man was fatally shot by police after he wounded two officers. AP hide caption

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A crowd gathers at a press conference and rally in front of Manhattan federal court to vocalize their objection to the stop and frisk policy by the police Department Wednesday, March 27, 2013, in New York. The Center for Constitutional Rights has brought a lawsuit on behalf of four black plaintiffs who claim they were stopped by police because of their race. (AP Photo/ Louis Lanzano) Louis Lanzano/ASSOCIATED PRESS hide caption

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