In this April 3, 2014 photo, Northern Illinois University police officer Maria Christiansen checks on NIU senior Juan Martinez during a floor hockey game on campus before calling paramedics to assist in DeKalb, Ill. Christiansen, a survivor of the Feb. 14, 2008 NIU school shooting that injured 21 and killed five students, works the night shift on campus patrol. (AP Photo/Daily Chronicle, Danielle Guerra) MANDATORY CREDIT
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