Numbers 35:25-27

Thomson(i) 25 and the congregation shall deliver the slayer from the avenger of blood, and the congregation shall send him back to the city of his refuge, to which he fled; and he shall dwell there, till the death of the high priest, whom they have anointed with holy oil. 26 And if the manslayer go out of the bounds of the city of his refuge to which he fled, 27 and the avenger of blood find him out of the bounds of the city of his refuge, and the avenger of blood kill the slayer, he is not guilty of death.