PROBLEM:
A man is dead in a puddle of blood and water on the floor of a locked windowless room.  What happened?.
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HINT 1:
Question: Was any other person, object, weapon, or other item in the room?

Answer: No.
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HINT 2:
Question: Did the man die from his own doing?

Answer: Yes .
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SOLUTION:
The man committed suicide with an icicle.