An archivist was found dead in a secure basement archive room, surrounded by rare medieval manuscripts. The heavy steel fire door was locked from the outside by a digital keypad. The coroner noted the cause of death was smoke inhalation, yet there was no soot on the walls, no burned books, and no fire damage anywhere in the room. How did the killer pull off the murder?
Halon suppression
Archive rooms often use gas fire suppression systems (like Halon or CO2) that displace oxygen to put out fires without water. The killer triggered the system remotely, suffocating the victim without burning any paper.
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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