As investigators follow up on leads in the Boston Marathon bombing, the Boston Herald talks to security experts who say the attack may have been nearly impossible to prevent. That's because the use of an IED is "hard to stop ... in a free and open society," one expert explains. The device is easily hidden in a backpack, and since there were so many people at the event, it would have been impossible to check all bags. A retired FBI bomb technician echoes that sentiment, and adds that, "It would take some coordination, some know-how, and some intelligence," but "a one-man operation could easily do something like this."
So how to prevent something similar? The first expert says we need to focus on controlling "homemade explosive precursors." As for the bombs, they were small and, according to initial tests, crude—no C-4 or high-grade explosives, CNN reports. The FBI has taken the lead on the investigation, which also involves a number of agencies, but little is known so far and no suspects have been identified. Still, investigators are currently tracking "a number of active leads." (Read more Boston stories.)