Joshua 20:4-6

The one who has committed manslaughter shall escape for protection to one of these cities and stand at the entrance to the city gates and explain his case to the leaders of the city. The leaders must then receive him into their city and grant him asylum. When the one looking for revenge comes after him, the leaders of the city must protect him and not hand him over, for he killed the person accidentally and without premeditation. He must remain in the city until he has had a public trial; then he must remain protected in the city until the man who is high priest at that time has died. Afterward, he may return to his family and his own hometown.”