The lid of a pressure cooker was found on a roof near the scene of the Boston Marathon bombings, a federal law enforcement official with firsthand knowledge of the investigation tells CNN.
One of the bombs was housed in a pressure cooker hidden inside a backpack, the FBI said in a Joint Intelligence Bulletin. The device also had fragments that may have included nails, BBs and ball bearings, the agency said.
The second bomb was also housed in a metal container, but there's not enough evidence to determine whether it was also in a pressure cooker, the FBI said.
Discovery of the lid could yield vital clues as to the origin of the bomb.
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