This undated photo provided by Bill Richard, shows his son, Martin Richard, in Boston. Martin Richard, 8, was among the at least three people killed in the explosions, Monday, April 15, 2013, at the finish line of the Boston Marathon. (AP Photo/Bill Richard)

This undated photo provided by Bill Richard, shows his son, Martin Richard, in Boston. Martin Richard, 8, was among the at least three people killed in the explosions, Monday, April 15, 2013, at the finish line of the Boston Marathon. (AP Photo/Bill Richard)