Numbers 35:19-21

19The avenger of blood is to put the murderer to death; when he finds him, he is to kill him.

20Likewise, if anyone maliciously pushes another or intentionally throws an object at him and kills him, 21or if in hostility he strikes him with his hand and he dies, the one who struck him must surely be put to death; he is a murderer. When the avenger of blood finds the murderer, he is to kill him.