A priceless diamond was stolen from a glass case inside a locked mansion. Three suspects were present: the butler, the cook, and the gardener. Each blamed someone else. The butler said, 'The cook did it while baking.' The cook said, 'The butler did it during dinner prep.' The gardener said, 'I was outside all day.' Detective Thorne knew that only the thief lied, and the other two told the truth. Who stole the diamond?
The butler
If the gardener is telling the truth, then the butler and the cook both claim the other did it. Since only one person can be the thief (and thus lie), one of their statements must be true and the other false. If the butler is the thief, the cook tells the truth, the gardener tells the truth, and the butler lies—making the statements fit the 'only one liar' rule.
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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