satchel, pressure cooker in it. it would be pretty heavy, 30 pounds. another one in a backpack maybe and walked down the street and placed one, placed the other. now bombings are often some of the hardest crimes to solve because much of the evidence is blown up. what are officials doing right now to try to piece this crime together and track down whoever is responsible? well, aft, fbi, police bomb squad detectives are expert at reconstructing these devices from the blast. we do it all the time. blow up cars, we blow up bombs. we blow up pressure cookers. we put the pieces back together. so we can actually recognize bits of wire, battery parts, clock parts, circuit board parts and minutely put those together and the forensic scientist at the lab can help them put together. all right, jim cavanaugh, thank you so much. the heightened state of alert after the twin bombings in boston stretches overseas to day where a massive security