The detective who knew the laws of physics

Detective walked into a room with no windows and found a dead man, who  was hanging from the ceiling, which is 12 feet above floor level.

There was no chair beneath him that he might have jumped off of, or a table.

there was no chair and there was no other furniture that he could have used. The walls are all smooth and there is no way he could have used them to climb up.
However, the floor is flooded.

The detective could not see any way the man could have climbed the walls to get to where he is hanging.

Suddenly he realized that the man has hanged himself.

How did this man do it?