FBI Special Agent in Charge Richard DesLauriers speaks to reporters during a news conference, a day after two explosions near the finish line of the Boston Marathon killed three people and injured more than 170 others, in Boston, Massachusetts April 16, 2013. Police investigating the deadly blasts at the Boston Marathon said on Tuesday they had recovered fragments of black nylon that may been from a bag used to conceal one or both of the bombs detonated at the race, DesLauriers, the FBI official leading the probe said. REUTERS/Jessica Rinaldi (UNITED STATES - Tags: CRIME LAW SPORT ATHLETICS HEADSHOT)