If the man committed suicide, how did he do it?

Question

A man is found dead. When the investigation is done, he is found dead with a knife in his back. A chair sits beside him and the forensic team finds moisture around the body.

If he committed suicide, how did he do it?

Answer 1

The knife's handle probably is on a ice cube then placed on the ground pointing upward. The man fall himself down to the point of the knife where he used the chair to level himself up.

Answer 2

It's knife at the back or knife wound at the back..?
... Knife of ice is the right answer , if the knife was not found at the back..