'Avenger of Blood' in the Bible

The avenger of blood shall himself put the murderer to death: when he meeteth him, he shall put him to death.

or in enmity smote him with his hand, so that he died; he that smote him shall surely be put to death; he is a murderer: the avenger of blood shall put the murderer to death, when he meeteth him.

then the congregation shall judge between the smiter and the avenger of blood according to these ordinances;

and the congregation shall deliver the manslayer out of the hand of the avenger of blood, and the congregation shall restore him to his city of refuge, whither he was fled: and he shall dwell therein until the death of the high priest, who was anointed with the holy oil.

and the avenger of blood find him without the border of his city of refuge, and the avenger of blood slay the manslayer; he shall not be guilty of blood,