Deuteronomy 19:11
But if any man hate his neighbour, and lie in wait for him, and rise up against him, and smite him mortally that he die, and fleeth into one of these cities: But if any man hate his neighbour, and lie in wait for him, and rise up against him, and smite him mortally that he die, and fleeth into one of these cities:
The case is deliberate murder: a man hates his neighbor, lies in wait for him, rises up against him, strikes him so that he dies, and then flees into one of the cities of refuge. Hatred and lying in wait mark intent, distinguishing this killing from an accidental or unwitting killing. Therefore the willful murderer is not entitled to remain under the refuge provisions for the accidental killer but is to be delivered for punishment.
Flight to the city protects the slayer from immediate private vengeance but not from the legal consequences of murder, with guilt to be determined by a fair trial. The elders' initial decision at the city gate admitted a fugitive to the city, and a full trial before a higher court followed after witnesses and accusers could be brought forward. The stern law of a life for a life rigidly applies, and it is the murdered man's Goel as avenger of blood whose duty it is to exact the penalty by slaying the murderer himself when he meets him, because there were no civil officers to execute the murderer. This regulation of blood revenge belongs to the later Mosaic code, restricting an earlier form of the law already present in patriarchal times.
The word translated mortally is the Hebrew nephesh, the same word elsewhere translated soul, so to smite him mortally is to smite his soul. Its use for a man struck so that he dies shows the soul means the physical person and is liable to death. Thus the soul is subject to physical death rather than naturally never-dying.