Numbers 35:16-24, 30-31

‘But if he strikes him with an iron implement, so that he dies, he is a murderer; the murderer shall surely be put to death. And if he strikes him with a stone in the hand, by which one could die, and he does die, he is a murderer; the murderer shall surely be put to death. Or if he strikes him with a wooden hand weapon, by which one could die, and he does die, he is a murderer; the murderer shall surely be put to death. The avenger of blood himself shall put the murderer to death; when he meets him, he shall put him to death. If he pushes him out of hatred or, while lying in wait, hurls something at him so that he dies, or in enmity he strikes him with his hand so that he dies, the one who struck him shall surely be put to death. He is a murderer. The avenger of blood shall put the murderer to death when he meets him. ‘However, if he pushes him suddenly without enmity, or throws anything at him without lying in wait, or uses a stone, by which a man could die, throwing it at him without seeing him, so that he dies, while he was not his enemy or seeking his harm, then the congregation shall judge between the manslayer and the avenger of blood according to these judgments.

Whoever kills a person, the murderer shall be put to death on the testimony of witnesses; but one witness is not sufficient testimony against a person for the death penalty. Moreover you shall take no ransom for the life of a murderer who is guilty of death, but he shall surely be put to death.