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Massachusetts Institute of Technology police officers march as they depart St. Patrick's Church in Stoneham, Mass., following a funeral Mass for MIT police officer Sean Collier, Tuesday, April 23, 2013. Collier was fatally shot on the MIT campus Thursday, April 18, 2013. Authorities allege that the Boston Marathon bombing suspects were responsible. Law enforcement official at right is unidentified. (AP Photo/Steven Senne)

Boston deals with aftermath

Two bomb explosions killed three and injured more than 140 at the Boston Marathon, April 15. The bombs left a city forever changed, and people putting the pieces back together after the brutal chapter comes to a close.