Cities of refuge
In Numbers 35, we read about the cities of refuge providing protection for whoever “kills a person without intent.” In the description of the cities of refugee, we find an interesting detail: an unintentional murderer must remain in the city of refuge till the death of the High Priest. When the High Priest dies, he may return to his home, without fear of a revenge. Why? How is the death of the High Priest relevant?
How did the High Priest save them?
Centuries later, Jewish interpreters explain in the Talmudic discussion that homicide is a sin which must be atoned. Even an unintentional murder cannot be compensated by a ransom (Num.35:31) — the blood must be redeemed by the death of the murderer. According to this interpretation, because it is an unintentional murder, only the death of the High Priest may be a proper atonement. Once the High Priest dies, the blood is redeemed and the slayer is free.
See the connection between the Torah and the New Testament
This seemingly unexpected link between the time of asylum and the death of the High Priest is a statement of the fact that, only death can atone for the blood. Thus, for the first time in the Bible, the death of the High Priest becomes an atoning event. The New Testament authors picked up on this Hebrew Bible intuition and elaborated on it.