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Big question: lone-wolf bomber, or organized terrorism?

The Boston Globe's Steve Silva talks to NBC's Brian Williams about the footage he shot at the moment explosions rocked the finish line of Monday's Boston Marathon.

The first task for investigators in the bombing that rocked Boston on Monday will be determining whether the carnage was the work of an individual or a terrorist organization, experts said.

The scope of the attack at the high-security Boston Marathon doesn’t rule out a lone wolf, said Evan Kohlmann, NBC News’ terrorism analyst.

“There have been individuals who have been capable of doing something like this,” Kohlmann said, pointing to the 1996 Olympics bombing by anti-abortion radical Eric Rudolph.

But Kohlmann said an organized group – domestic or international – could also be the culprit.

“It could be half a dozen different causes, or just a crazy guy,” he said.

NBC News National Security analyst Mike Leiter agreed that even though it was a “pretty sophisticated attack,” the field of suspects is wide open.

“I wouldn’t go down any particular path,” Leiter said on MSNBC.

William Bratton, the former police commissioner of Boston, Los Angeles and New York, said it's important investigators approach the case with an open mind.

"You start with the assumption that you know nothing," he said.

They also need to be on the alert for false claims of responsibility that "will come out of the woodwork," Bratton said.

Kohlmann said forensics from the scene could give investigators important information. If the explosive used was military-grade, that would suggest foreign terrorists, and not someone closer to home jury copying bomb-recipes off the Internet, is responsible.

The most crucial clues, though, will come from closed-circuit camera footage from the area that could show the bomber planting the devices or fleeing the scene, he said.

He noted that in the 2005 London subway bombings, police used the cameras to quickly zero in on the suspects.

“My suspicion is this is something that they will be able to make significant progress on in a very short period of time,” Kohlmann said.

“The record of people who have gotten away with things like this is not very good.”