Sanhedrin 77 - No Liability for Indirect Killing
Someone bound his fellow by the seashore, then caused a stream of water to sweep over him, and thereby killed him. This was done thus - he made a hole in a dam that stood between the water and the victim, so that the water would gush out and drown the victim. In such a case, the water is considered like arrows that he shot at the victim, and he is liable to execution.
However, this is only so when the water that reached the victim fell on him immediately after the barrier was breached. If some time lapsed before the water reached the victim, it is no longer considered the perpetrator's primary force, and he is not liable.
As a general principle, one is liable for murder only if it was caused by his direct force, not by any removed or consequential action, and of course if he has been properly warned a short while before the action.
Art: William Payne - Landscape with a waterfall