In Parshas V'etchanan the three arei miklat, the cities of refuge for the unintentional murderer, are designated on the east side of the Yarden (Jordan River). Upon the Jewish people's entering Eretz Yisroel proper, another three cities were to be set up on the west side of the Jordan. Chazal note that it is strange that the cities were divided evenly between both sides of the Yarden even though there were 9.5 shevatim (tribes) on one side and only 2.5 on the other. Chazal, in explaining this phenomenon, note that there were more murders that occurred on the east side of the Yarden, thereby necessitating a higher ration of arei miklat to people. What caused this phenomenon? What was it about this half of Eretz Yisrael that led to a laxity of concern for human life which lead to unintentional murders being more rampant?
The halacha is that a rotzeach beshogeg must remain in the ir miklat until the death of the kohen gadol. The Torah is telling us that there is some connection between the chet of retzicha beshogeg and the kohen gadol.
We find in other areas of halacha that the Beit Hamikdash embodies the antithesis of disregard for human life. For example, the Torah prohibits using stones touched by iron for the mizbeach because iron, which is used to form weapons, is responsible for loss of human life. If even an unintentional murder takes place it indicates that the Beit Hamikdash is not fulfilling its role. The kohen gadol, the guardian of the Beit Hamikdash is also at fault to a certain degree, and he too shares in the punishment of rotzeach beshogeg.
It is this role of the Beit Hamikdash- the preserving of human life - that may account for the laxity of attitude towards human life that existed on the east side of the Yarden, in that the Beit Hamikdash was on the far side of the river. The 2.5 shevatim that lived on the east side always felt a lack of closeness to the Beit Hamikdash because of the geographical separation that existed. In Sefer Yehoshua, residents of the east side of the Yarden constructed a mizbeach to remind their children of the mishkan and later the Beit Hamikdash that would built on the western side. This sense of distance led to deterioration in the value of human life, and carelessness that ultimately resulted in a higher rate of unintentional murder.
Furthermore, the Beit Hamikdash teaches us about the sanctity of life. The Ramban understands the aspect of korbanot as kaparah being the greatest affirmation of life. Based on strict justice, a person who sins should die. Hashem gives us a second chance at life upon entering the Beit Hamikdash. For this reason the kohen must be synonymous with life and distance himself from all contact with death. One who understands the inner message of the Beit Hamikdash has a greater appreciation of life, and learns to value it and treat it with greater care.