Law enforcement evidence technicians are seen behind a U.S. flag placed at a memorial for the victims as they continue to search the scene of the Boston Marathon bombings for evidence in Boston, ... more 
Law enforcement evidence technicians are seen behind a U.S. flag placed at a memorial for the victims as they continue to search the scene of the Boston Marathon bombings for evidence in Boston, Massachusetts in this April 20, 2013 file photo. Tuesday marks the one-year anniversary of the Boston Marathon bombing on April 15, 2013, when two Chechen brothers allegedly planted pressure-cooker bombs near the race's finish line, killing three people and wounded more than 260. REUTERS/Jim Bourg/Files (UNITED STATES - Tags: CRIME LAW CIVIL UNREST ANNIVERSARY) less 
1 / 24
Reuters | Photo By JIM BOURG / Reuters
Mon, Apr 14, 2014 2:01 AM EDT