May not be a gunshot. We had a series of "shootings" here some years back, where cars on the freeway were getting their windows blown out by someone. The cops could never find bullet fragments. Then they noticed lots of glass marbles lying around in the areas where the shootings were happening. They finally came to the realization that someone was perched up on a hilltop, firing marbles with a slingshot. THe marbles would shatter and mix in with the glass fragments, which is why they didn't know this was happening until whole marbles were found. If they don't find bullet fragments in this case, I'd put money on the marble/slingshot theory.
Liberals should use SPITBALLS in their slingshot.