The FBI’s lead investigator into the Boston Marathon bombings on Tuesday made a passionate plea for information from the public, saying the “range of suspects and motives remains wide open” as the probe into who might be responsible for the attacks begins. “Someone knows who did this,” said Richard DesLauriers, the special agent in charge of the FBI’s Boston office. “Importantly, the person who did this is someone’s friend, neighbor, coworker or relative. We are asking anyone who may have heard someone speak about the marathon, or the date of April 15, in any way that indicated that he or...