Num. 35:33
So, you shall not pollute the Land in which you are dwelling. Blood pollutes the Land; and no atonement can be made for the Land that was defiled by blood, except the blood of him who shed it.”
As explained in the first nine verses of Deuteronomy 21, the blood of an unworked red heifer could bring forgiveness for the Land that had been defiled by bloodshed if it was unknown who was responsible.
The point being made in Numbers 35 is that no ransom price could atone for murder. The convicted murderer had to be put to death. This is explained two verses earlier. Num. 35:30-31
Whoever kills any person, the murderer shall be slain at the mouth of witnesses. But nobody shall be put to death on the testimony of one witness.
Moreover, you shall take no ransom for the life of a murderer that is guilty of death. But he shall surely be put to death.”
It was not simply bloodshed that polluted the promised Land. YHWH declared through His prophet Jeremiah that it was polluted by idolatry and all sorts of wickedness. Jer. 3:2
…. you have polluted the Land with your whoredoms and with your wickedness.”
Moreover, murder was not the only crime that carried the death penalty. Hitting one’s parents, kidnapping, cursing one’s parents, not locking up a dangerous animal, committing any sexually immoral act, working on the Sabbath, sacrificing one’s child to Molech, approaching that which only pertains to the Levites, uttering YHWH’s name while cursing Him, defiantly disobeying Him, or causing others to disobey Him were all capital offenses.
It should also be noted that when the judges sentenced someone to death at the mouth of two or three eyewitnesses, only the criminal would be punished for his/her transgression. Deu. 24:16
The fathers shall not be put to death for the children, neither shall the children be put to death for the fathers. One according to his sin will be put to death”
When Jeremiah prophesied the New Covenant, he confirmed these words. Jer. 31:30, 31
But every one shall die for his own iniquity: every man that eats the sour grape, his teeth shall be set on edge.
Behold, the days come, says YHWH, that I will renew a covenant with the house of Israel and Judah”
Ezekiel also confirmed these words when speaking of the Good News. Eze. 18:20, 23
The soul that sins [a sin worthy of death], shall die. The son shall not bear the iniquity of the father, neither shall the father bear the iniquity of the son:
Righteousness cannot be transferred to another person, and sin cannot be transferred to another person.
“Have I any pleasure at all that the wicked should die?” says the Master YHWH: “and not that he should return from his ways, and live?”