Federal investigators search for evidence at the scene of the Amtrak Sunset Limited wreckage near Hyder, Ariz., the day after the derailment. Eric Drotter/AP hide caption

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Detective Mark Williams (right) speaks with an officer in Richmond, Va. A decade ago, amid a surge in violent crime, Richmond police were identifying relatively few murder suspects. So the police department refocused its efforts to bring up its "clearance rate." Alex Matzke for NPR hide caption

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FBI headquarters in Washington. An independent review says the bureau has made strides since Sept. 11 but "needs to accelerate its implementation of reforms." Pablo Martinez Monsivais/AP hide caption

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Amid much speculation by private security analysts, the FBI stood by its claim this week that North Korea was responsible for the hack against Sony Pictures. Damian Dovarganes/AP hide caption

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The Rev. Martin Luther King makes a statement at the Justice Department in Washington on Dec. 1, 1964 after a meeting with FBI Director J. Edgar Hoover. Under Hoover's leadership, the FBI investigated King and his personal life for years. Bob Schutz/AP hide caption

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FBI Director James Comey says new encryption features allow people "to place themselves beyond the law." Alex Wong/Getty Images hide caption

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This image obtained by NPR shows Ahmed al-Moflihi, a Yemeni-American who is believed to have fought in the Syrian civil war. NPR hide caption

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