Investigators Focusing on Type of Explosive Devices Used in Boston Bombing

Could provide clues on perpetrators

Authorities trying to track down the perpetrators of the Boston Marathon bombings that killed 3 people and injured more than 141 are focusing Tuesday on the type of devices used in the twin blasts for possible clues on who was behind the terror attack.

Among the dead in Monday's horrific attack is 8-year-old Martin Richard from Dorchester, whose mother and sister were also badly injured, theBoston Globe reported. Martin was the son of Bill Richard, a community leader from Dorchester's Ashmont neighborhood, officials told the newspaper