Deuteronomy 19:10-13

10So innocent blood will not be shed in the midst of your land which the Lord your God gives you as an inheritance, and 1bloodguiltiness be on you.

11“But 2if there is a man who hates his neighbor and lies in wait for him and rises up against him and strikes 3him so that he dies, and he flees to one of these cities, 12then the elders of his city shall send and take him from there and deliver him into the hand of the avenger of blood, that he may die. 1345You shall not pity him, but 6you shall purge the blood of the innocent from Israel, that it may go well with you.