Chromosomes and double helix over silhouettes of man Lee Woodgate/Ikon Images/Getty Images hide caption

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Photos of victims of the mass shooting at Umpqua Community College in Roseburg, Ore., are displayed behind Portland Police Sgt. Peter Simpson (left) and Douglas County Sheriff John Hanlin. Rich Pedroncelli/AP hide caption

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Former Sheriff William "Dub" Lawrence, in a scene from the documentary Peace Officer. It's not his job to investigate old crimes and officer-involved shootings — but that hasn't stopped him from obsessing over them. Courtesy of the artist hide caption

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The funeral for Harris County Sheriff Deputy Darren Goforth was held Sept. 4 in Houston. After Goforth was fatally shot at a gas station on Aug. 29, some spoke about a "war on cops." But while 2014 did see more officer deaths than 2013, one expert says that's not a sign of a statistically significant spike. Aaron M. Sprecher/Getty Images hide caption

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Investigators stand next to evidence markers in front of the house of Matthew Stewart, who was shot and injured by Ogden police during a drug raid, in Ogden, Utah, Jan. 5, 2012. One police officer was killed and five were wounded in the shootout that erupted as a narcotics enforcement team executed a search warrant at Stewart's home. George Frey/Reuters/Landov hide caption

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Jubin Fallahi enjoys a smoke at the Medina Hookah Lounge in Seattle. There are 11 known hookah lounges in the city, and the mayor wants to shut them all down. Martin Kaste/NPR hide caption

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On Wednesday, Hamilton County prosecutor Joe Deters announced murder and manslaughter charges against University of Cincinnati police Officer Ray Tensing for the traffic stop shooting death of motorist Samuel DuBose. During the press conference, Deters said that "being police officers shouldn't be the role of this university." John Minchillo/AP hide caption

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A cell at New York's Rikers Island jail. About 1,000 people die in American jails every year, and about a third of those are suicides. Seth Wenig/AP hide caption

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Inmates at California's Chino State Prison exercise in the prison yard in 2010. A proposition that was passed in the state last year reclassified certain crimes, releasing thousands of inmates earlier than had been anticipated. Kevork Djansezian/Getty Images hide caption

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