Parashat Mas’ei describes the Arei Miklat, cities in which those who kill by accident must remain until the death of the Kohein Gadol. Why is the killer allowed to leave after the death of the Kohein Gadol? Does his death cleanse the killer of his crime?
We can find an answer by asking another question. What is the true purpose of the Arei Miklat? The Arei Miklat are usually described as cities where those whose negligence caused another’s death go to protect themselves from the wrath of the victim’s family. This is definitely true at first, when the murderer arrives at one of the Arei Miklat. However, the killer is then taken to Beit Din to evaluate if the murder was not performed deliberately. If he is found to be innocent of willful murder, the killer goes back to the Ir Miklat, and stays there until the Kohein Gadol dies. It is clear from the fact that the killer returns to the Ir Miklat that the city is not simply to protect him. So what is the point of returning?
The answer is that the role of the Ir Miklat is not to protect the killer; rather, it is for the sake of the land. The Parashah records, “VeLo Tachanifu Et HaAretz Asher Atem Bah, Ki HaDam Hu Yachanif Et HaAretz, VeLaAretz Lo Yechupar, LaDam Asher Shupach Bah, Ki Im BeDam Shofecho,” “You shall not pollute the land in which you live; for blood pollutes the land, and the land can have no expiation for blood that is shed on it, except by the blood of he who shed it” (BeMidbar 35:33). Ibn Ezra explains that this Pasuk is referring to unintentional murderers. Even one who murdered by mistake is considered to have polluted the Earth with blood. He is therefore forced to go to a place where the soil is not tilled and the land not blessed.
We are still left wondering about the role of the Kohein Gadol. It is his job to atone for the sins of the Jews. It is explained that the goat he brings every year on Yom Kippur to be thrown off of a cliff to its death, known as the Sa’ir LaAzazel, purifies the land of innocent bloodshed without intent. However, it is unknown when the land will be purified for which sin, as we do not know the severity of each sin in Hashem’s eyes. Therefore, we assume that at the end of the Kohein Gadol’s life, every sin has been atoned for. The negligent killer will not be polluting the Earth by leaving the Ir Miklat after his death.
The Torah treats manslaughter as "polluting the land." Thus, it is evident that intentional murder has an unthinkable effect on the county and society as a whole.