Deuteronomy 21:6-9

6And all the elders of that city, that are next unto the slain man, shall wash their hands over the heifer that is beheaded in the valley:

7And they shall answer and say, Our hands have not shed this blood, neither have our eyes seen it.

8Be merciful, O Lord, unto thy people Israel, whom thou hast redeemed, and lay not innocent blood unto thy people of Israel’s charge. And the blood shall be forgiven them.1

9So shalt thou put away the guilt of innocent blood from among you, when thou shalt do that which is right in the sight of the Lord.