Bridgeway Bible Commentary - Deuteronomy 21:1-23
Respect for human life (21:1-23)Murder made the land unclean, and the uncleanness could be removed only by the execution of the murderer (see Numbers 35:29-34). Where the murderer could not be found, the elders of the town nearest the place of the murder had to go to an unpolluted stream nearby and carry out the ritual slaughter of a young cow instead of the unknown murderer. The blood of the cow washed away in the stream symbolized the removal of uncleanness caused by the unlawful bloodshed... read more
Joseph Benson's Commentary of the Old and New Testaments - Deuteronomy 21:22
Deuteronomy 21:22. On a tree Which was done after the malefactor was put to death some other way; this public shame being added to his former punishment. read more