This is what God said to Moses about the penalty for murder.

Numbers 35:16-21. If he struck him down with an iron object, so that he died, he is a murderer; the murderer shall surely be put to death. If he struck him down with a stone in the hand, by which he will die, and as a result he died, he is a murderer; the murderer shall surely be put to death.  Or if he struck him with a wooden object in the hand, by which he might die, and as a result he died, he is a murderer; the murderer shall surely be put to death. The blood avenger himself shall put the murderer to death; he shall put him to death when he meets him. If he pushed him of hatred, or threw something at him lying in wait and as a result he died, or if he struck him down with his hand in enmity, and as a result he died, the one who struck him shall surely be put to death, he is a murderer; the blood avenger shall put the murderer to death when he meets him.