Deuteronomy 21:4-6

Amplified Bible

⁴ and the elders of that city shall bring the heifer down to a [river] valley with running water, which has not been plowed or planted, and shall break the heifer’s neck there in the valley. ⁵ Then the priests, the sons of Levi, shall approach, for the Lord your God has chosen them to serve Him and to bless in the Name (Presence) of the Lord; and every dispute and every assault (violent crime) shall be settled by them. ⁶ All the elders of that city nearest to the dead man shall wash their hands over the heifer whose neck was broken in the valley;