A note left at a crime scene fades completely after a few hours. What explains this disappearance?

Category: Mystery · Difficulty: hard

Hint: Focus on methods where messages vanish intentionally after some time.

Answer

Invisible ink revealed by heat initially

Explanation

Invisible inks can appear only under specific conditions and then fade naturally.

This is a hard mystery riddle — a tricky one that takes a little thought. The answer is Invisible ink revealed by heat initially.

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