At midnight, a wealthy collector was found shot in his locked study. The window was bolted from the inside, and the heavy oak door was locked with the key still in the keyhole on the inside. A gun lay beside him with his own fingerprints on it. The coroner noted the shot came from across the room, yet no bullets entered through the glass. How did the killer pull off a locked-room shooting?
The collector used an icicle gun, or the gun was frozen water containing a projectile that melted away completely.
Since no bullet or conventional weapon was left intact other than a gun that didn't fire a normal metal slug, a melting ice bullet solved the physics of the closed room.
About this riddle
Detective riddles are tiny mysteries. Look for the detail in the story that does not fit; it is usually the clue that solves the case.
Difficulty: Hard. More like this: Detective riddles with answers or try Truth & Lie Island for a different kind of puzzle.
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