President Obama is the first sitting president to visit a federal prison. Kevin Lamarque/Landov hide caption

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Janice Bellucci, a lawyer, and Frank Lindsay serve on the board of directors of California Reform Sex Offender Laws, which advocates on behalf of registered sex offenders like Lindsay. Chloe Prasinos/NPR hide caption

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Attorney General Loretta Lynch speaks about a federal crackdown on Medicare fraud. With her are HHS Inspector General Daniel R. Levinson (from left), HHS Secretary Sylvia Mathews Burwell, FBI Director James B. Comey and Assistant Attorney General for the Criminal Division Leslie R. Caldwell. T.J. Kirkpatrick/Getty Images hide caption

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Oakland police officers, wearing body cameras, form a line during demonstrations against recent incidents of alleged police brutality nationwide. Elijah Nouvelage/Getty Images hide caption

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Dallas Mildenhall, New Zealand's forensic pollen expert, peers at samples through a microscope. Courtesy of David Wolman 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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Oklahoma's Buddy Hield (right) and Denzel Valentine of Michigan State played in Friday's East Regional Semifinal of the 2015 NCAA tournament in Syracuse. If you've got money riding on this year's NCAA tournament, you might want to hear about what happened to John Bovary's football pool. Maddie Meyer/Getty Images hide caption

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In December, New York Mayor Bill de Blasio met with youth offenders at alternative housing on Rikers Island. A new state proposal would spare teens younger than 18 from serving time in adult prisons. Susan Watts/ASSOCIATED PRESS hide caption

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Some of the artifacts that were handed over to Iraq during a ceremony Monday in Washington, D.C. Jackie Northam/NPR hide caption

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Some colleges and police departments are starting to use software that scans social media to identify local threats, but most tips still come from members of the public. Ikon Images/Getty Images hide caption

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