Numbers 35:19
19 eThe avenger of blood shall himself put the murderer to death; when he meets him, he shall put him to death.
Numbers 35:21
21 or in enmity struck him down with his hand, so that he died, then he who struck the blow shall be put to death. He is a murderer. eThe avenger of blood shall put the murderer to death when he meets him.
Deuteronomy 19:12
12 then the elders of his city shall send and take him from there, and hand him over to the avenger of blood, so that he may die.