Luke talks to friend and host of "Wait, Wait, Don't Tell Me" Peter Sagel. Sagel was assisting a blind man run the Boston Marathon. They finished just minutes before the first bomb went off. // New details are coming out about the bombs used the Boston bombings. We talk to Jimmie Oxley, a professor at the University of Rhode Island and expert on bomb-making materials. // As investigators try to figure out what happened during the bombings at the Boston Marathon, they'll comb through thousands of hours of video taken at the scene of the explosions. Police are asking anyone with pictures to step forward. // U.S. law enforcement officials say a Saudi national injured in the Boston Marathon bombing is regarded as a witness, not a suspect. It was previously reported that he might be a suspect.