Joshua 20:6

20:6 He must remain in that city until his case is decided by the assembly and the high priest dies. Then the one who committed manslaughter may return home to the city from which he escaped.”

Joshua 20:9

20:9 These were the cities of refuge appointed for all the Israelites and for resident foreigners living among them. Anyone who accidentally killed someone could escape there and not be executed by the avenger of blood, at least until his case was reviewed by the assembly.