הלכות רוצח ושמירת הנפש

Whenever a person kills unintentionally, he should be exiled from the city in which he killed, to a city of refuge. It is a positive mitzvah to exile him, as implied by Numbers 35:25: "He shall dwell there until the death of the High Priest."
The court is admonished not to accept a ransom from the killer to enable him to remain in his city, as Ibid.:32 states: "You shall not accept a ransom so that he will not have to flee to his city of refuge."

A person who kills unintentionally is not exiled unless the person whom he kills dies immediately. If, however, he wounds a person unintentionally - even though the court assesses that the victim will die - and the victim indeed falls sick and dies, the killer is not exiled. The rationale is that the death may not have been entirely the killer's fault; perhaps the victim in some way hastened his own death or wind entered his wound and caused him to die.
Even if the killer severed the victim's windpipe and esophagus, if the victim remained alive for a short while, the killer is not exiled on his accord. Therefore, it is only when the victim died without entering any death spasms at all, or was killed in a place that was not open to the wind - e.g., a closed marble building, or the like - that the killer is exiled.

When a Jew unintentionally kills a servant or a resident alien, he must be exiled. Similarly, if a servant unintentionally kills a Jew or a resident alien, he should be exiled.
Similarly, a resident alien who kills another resident alien or a servant unintentionally should be exiled, for the passage concerning the cities of refuge, Numbers 35:15, describes them as being for "the children of Israel, an alien and the residents among you."

When a resident alien kills a Jew unintentionally, he should be executed, even though he acted unintentionally. The rationale is that a person must always take responsibility for his conduct.
Similarly, if a resident alien kills another resident alien because he thought that it was permitted to kill, he is considered to be close to acting intentionally, and he should be executed, for he intended to kill.
When one gentile kills another gentile unintentionally, the cities of refuge do not serve as a haven for him, for the above verse states: "For the children of Israel."

When a son unintentionally kills his father, he should be exiled. Similarly, when a father unintentionally kills his son, he should be exiled.
When does the above apply? When the father kills the son while not in the midst of Torah study, or when he was teaching his son a profession that is not necessary for him. If, however, he imposes punishment on his son while teaching him Torah, secular knowledge or a profession, and the son dies, the father is not liable for exile.

Similarly, when a teacher strikes a student or an emissary of the court strikes a litigant who refuses to appear in courtand accidentally kills him, he is not liable for exile.
This concept is derived from Deuteronomy 19:5, which mentions the punishment of exile for a person who unintentionally kills a colleague while "chopping wood" - i.e., a permitted act. Thus, this punishment is not imposed when a father strikes a son, a teacher strikes a student, or an emissary of the court strikes a litigant, for they unintentionally killed while performing a mitzvah.

At the outset, both a person who killed unintentionally and one who killed intentionally should flee to a city of refuge. The court in the city in which the killing took place sends for the killer and brings him back to that city, as ibid.:12 states: "And the elders of his city shall send and take him from there."
If the killer is condemned to execution, he should be executed, as ibid. continues: "And they shall give him to the hand of the blood redeemer." If a person is absolved, he should be released, as Numbers 35:25 states: "And the congregation shall save the killer from the hand of the blood redeemer." And if the killer is sentenced to exile, he should be returned to his previous place, as ibid. continues: "And the congregation shall return him to his city of refuge."

When he is returned to his city of refuge, he is given two Torah sages to accompany him, lest the blood redeemer attempt to kill him on the way. They should tell him: "Do not deal with him in the manner of those who shed blood. It was unintentional that this happened."

The above applies whether he kills him on the road before he enters his city of refuge or if he kills him when returning together with the two who are guarding him. If he enters his city of refuge and intentionally departs beyond its Sabbath boundaries,he has granted license for his life to be taken. The blood redeemer is permitted to kill him. And if another person kills him, that other person is not liable, as Numbers 35:27 states: "There is no liability for his blood."

If the killer leaves his city of refuge unintentionally, whoever slays him - whether the blood redeemer or another person - should be exiled. If the killer is slain within the Sabbath limits of the city of refuge, the one who slayed him should be executed.

The altar in the Temple serves as a haven for killers. This is derived from Exodus 21:14, which states with regard to a person who kills intentionally: "You shall take him from My altar to die." One can derive from this, that one who kills unintentionally should not be killed at the altar.
Thus, if a person kills unintentionally and takes refuge at the altar, and the blood redeemer kills him there, he should be executed as if he killed him in a city of refuge.

What serves as a haven is only the top of the altar in the Temple. Moreover, it serves as a haven only for a priest who is in the midst of sacrificial worship. For a person other than a priest, a priest who is not involved in the sacrificial worship, or a priest who was involved in the sacrificial worship but was near the altar or holding on to its horns, the altar does not serve as a haven.