Numbers 35:26-28

VIN(i) 26 But if the killer surely goes out of the territory of the city of his refuge to which he fled, 27 and the avenger of blood find him outside the border of his city of refuge and the avenger of blood kills the manslayer, he will not be guilty of blood, 28 because he must live in the city of his refuge until the death of the high priest. But after the death of the high priest the killer will return to the land of his property.