John Calvin Commentary Deuteronomy 21:1

"If one be found slain in the land which Jehovah thy God giveth thee to possess it, lying in the field, and it be not known who hath smitten him;" — Deuteronomy 21:1 (ASV)

If one be found slain in the land. This supplement is of a mixed character, relating partly to civil and partly to criminal law. We are informed by it how precious the life of man is to God; for, if a murder has been committed by some unknown person, He requires an expiation to be made, by which the neighboring cities should cleanse themselves from the pollution of the crime. From this it appears that the earth is so polluted by human blood that those who encourage murder through impunity share in the guilt. The question here concerns a secret crime, the guilt of which attaches to the neighboring cities until, by a diligent inquiry, they can testify that the perpetrator has not been discovered; how much less excusable, then, will they be if they allow a murderer to escape with impunity?

The prescribed rite is that the elders of the nearest city should take a heifer that had never been yoked, bring it into a stony and barren valley, cut off its neck with the assistance of the priests, wash their hands, and bear witness that their hands, as well as their eyes, are pure, as they are not aware of the criminal. God chose a heifer that had never borne a yoke so that the satisfaction made by innocent blood might be represented more vividly. It was to be killed in a desolate place so that the pollution might be removed from the cultivated lands.

For if the blood of the heifer had been shed in the middle of the city’s marketplace, or in any inhabited spot, familiarity with the sight of blood would have made them callous to inhumanity. Therefore, for the purpose of awakening horror, it was led out into a solitary and uncultivated spot, so that they would thus be accustomed to detest cruelty. Although, properly speaking, this was not a sacrifice that could only be offered in the sanctuary, it still nearly approached the nature of a sacrifice, because the Levites were in attendance and a solemn supplication was made. Nevertheless, they were employed not only as ministers of the altar but also as judges, for their office is expressed in the words that they were chosen to minister to God, to bless the people, and to pronounce sentence as to every stroke.