Deuteronomy 21:6
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 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:
The washing of the hands over the beheaded heifer was a solemn public act by the elders of the city found nearest to the slain man. By it they openly declared that their own hands had not shed his blood and that their eyes had not seen who had done the deed. The ceremony was an expression of abhorrence for murder, declaring that those in authority were not to treat such a crime with carelessness or indifference. They were held responsible to employ every possible means to discover the wrongdoer and bring him to justice, and any negligence that shielded the guilty made them partakers in the evil and left them answerable for innocent blood.