Capt. Paul Carey of the Maryland Natural Resources police shows a side-scan sonar being used in a search on the Chesapeake Bay in 2006. In recent years, the cost of such equipment has come down, allowing more local law enforcement departments to purchase it. Chris Gardener/AP hide caption

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Los Angeles police officers take a break during a basketball game with residents of the Nickerson Gardens housing project in July 2011. Violent crime at Nickerson Gardens and two nearby housing projects has fallen by almost half since 2010. Thomas Watkins/AP hide caption

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An image taken from fired police sergeant Ron King's video statement, in which he defends himself for bringing silhouette targets resembling the hoody-wearing image of Trayvon Martin. YouTube hide caption

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A mine worker sings and dances during a gathering at the Lonmin Platinum Mine near Rustenburg, South Africa, on Wednesday. Some 270 miners were charged with murder Thursday in connection with the deaths of 34 of their striking colleagues. Themba Hadebe/AP hide caption

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Sleepy police were likelier to fall asleep while driving, a new survey of nearly 5,000 officers in the U.S. and Canada finds. About 40 percent of officers surveyed reported sleep disorders, with various health implications. Sean Locke/iStockphoto hide caption

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Occupy Oakland protesters set trash on fire to make a barricade as police officers form a line to disperse them on Nov. 3., in Oakland, Calif. Kimihiro Hoshino/AFP/Getty Images hide caption

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