Deuteronomy 21:8
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. 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.
When the slayer of a murdered person could not be discovered, the elders of the city nearest to the place of the killing were required to make a solemn public declaration disavowing any share in the bloodshed. In that declaration they were to plead for mercy toward the redeemed people Israel and ask that innocent blood not be laid to their charge. When they thus did what was right, the guilt of the blood was forgiven them. The ceremony was a lesson that those in authority must never deal with murder in a careless or indifferent manner, but must search into the matter with diligence, openly condemn the crime, and exert every effort to bring the guilty to justice. Any neglect that sheltered the murderer would involve those answerable for justice in a share of his guilt.