Deuteronomy 21:6-8

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