Numbers 35:17-19

17If he struck him down with a stone in the hand, by which he will die, and as a result he died, he is a murderer; the murderer 1shall surely be put to death.

18Or if he struck him with a wooden object in the hand, by which he might die, and as a result he died, he is a murderer; the murderer shall surely be put to death.

19The blood avenger himself shall put the murderer to death; he shall put him to death when he meets him.