Deuteronomy 19:10-12

Do this so that innocent blood will not be shed in your land, which the LORD your God is giving you as your inheritance, and so that you will not be guilty of bloodshed. But if out of hate someone lies in wait, assaults and kills a neighbor, and then flees to one of these cities, the killer shall be sent for by the town elders, be brought back from the city, and be handed over to the avenger of blood to die.