The Science: Examining a surviving microscope slide under a polarizing microscope, Palenik noted that the metal specks bore marks from the slicing instrument used to prepare them for mounting. That implied they were soft-most probably lead, not brass. Palenik cut through the slide cover, removed a sample, and halved it. First, the low-tech approach: He dissolved half the particle in solution, let it dry, then added potassium iodide. The ensuing reaction produced the yellow hexagonal plates typical of lead iodide (left, bottom). Next Palenik microprobed the other half with an X-ray spectroscopy detector, which provides elemental analyses. The result: lead again. The metal in King's scalp came from a bullet, not the railing, Palenik concluded. There was no second gunman.