Deuteronomy 21:7-8

They shall answer To the priests who shall examine them. This blood This about which the present inquiry is made; or this which is here present: for it is thought the corpse of the slain man was brought into the same place where the heifer was slain. Nor have we seen or understood how or by whom this was done. Forgiven Though there was no moral guilt in this people, yet there was a ceremonial uncleanness in the land, which was to be expiated and forgiven.