These new photos, taken of the scene of the Boston marathon attacks on Monday, show fragments of the two bombs that detonated at the finish line. The images—which show frayed wires, a misshapen battery pack, a bloody zipper-pull from a backpack, nails, a small green circuit board, and dented metal fragments—will provide clues to the anatomy of the bombs. Authorities are weeding through heaps of forensic evidence at the site to try to find some answers and track suspects.

[NBC, images via Joint Terrorism Task Force of Boston / Reuters]

[NBC, images via Joint Terrorism Task Force of Boston / Reuters]