'Avenger of Blood' in the Bible

The avenger of blood himself shall slay the murderer: when he meets him, he shall slay him.

Or in enmity strikes him with his hand, that he dies: he that struck him shall surely be put to death; for he is a murderer: the avenger of blood shall slay the murderer, when he meets him.

Then the congregation shall judge between the slayer and the avenger of blood according to these judgments:

And the congregation shall deliver the slayer out of the hand of the avenger of blood, and the congregation shall restore him to the city of his refuge, where he had fled: and he shall abide in it until the death of the high priest, who was anointed with the holy oil.

And the avenger of blood finds him outside the borders of the city of his refuge, and the avenger of blood kills the slayer; he shall not be guilty of blood: