Deuteronomy 21:6-9

6And all the elders of that city, who are nearest unto the slain man, shall wash their hands over the heifer whose neck was broken in the valley; 7and they shall answer and say, Our hands have not shed this blood, neither have our eyes seen it. 8Forgive, O Jehovah, thy people Israel, whom thou hast redeemed, and suffer not innocent blood to remain in the midst of thy people Israel. And the blood shall be forgiven them. 9So shalt thou put away the innocent blood from the midst of thee, when thou shalt do that which is right in the eyes of Jehovah.