Numbers 35:25-28

They must protect the killer from the dead person’s relative, sending the killer back to the original city of safety, to stay there until the high priest dies (the high priest had the holy oil poured on him). “ ‘Such a person must never go outside the limits of the city of safety. If a relative of the dead person finds the killer outside the city, the relative may kill that person and not be guilty of murder. The killer must stay in the city of safety until the high priest dies. After the high priest dies, the killer may go home.