3rd Puzzle

In the ancient days, came a man from a countryside to a small township for living better. But upon his utmost efforts, he failed and in a great depression. It was said that he had been fool and had disappeared. Several days later, someone found him in the empty house but he was dead. When a detective was called at the spot, he saw that the dead man still hanging there by a rope around his neck, and the other side of the rope tightened with the girders of the ceilings. On the ground there was still a pool of water. The house was totally empty and the girders were very high that the dead man could not reach the girders from the ground even plus the rope, but still could not get over there. Anyway, the detective at last got the answer that it was a suicide. But the question is how did he do that?