Deuteronomy Chapter 21, Verse 1

1: If one be found slain in the land which the LORD thy God giveth thee to possess it, lying in the field, and it be not known who hath slain him:- edit KJV text
1: When there shall be found in the land, which the Lord thy God will give thee, the corpse of a man slain, and it is not known who is guilty of the murder,— edit Douay text
1: And if one be found slain with the sword in the land, which the Lord thy God gives thee to inherit, having fallen in the field, and they do not know who has smitten [him];— edit LXX text