Deuteronomy 19:11-13

11“But if there is a man who hates his neighbor and lies in wait and ambush for him and attacks him and strikes him down so that he dies, and the assailant escapes to one of these cities,

12then the elders of his own city shall send for him and have him taken back from there and turn him over to the avenger of blood, so that he may be put to death.

13You shall not pity him [the guilty one], but you shall purge the blood of the innocent from Israel, so that it may go well with you.