Numbers 35:12, 21, 24, 27

The cities shall be to you as a refuge from the avenger, so that the manslayer will not die until he stands before the congregation for trial.

or if he struck him down with his hand in enmity, and as a result he died, the one who struck him shall surely be put to death, he is a murderer; the blood avenger shall put the murderer to death when he meets him.

then the congregation shall judge between the slayer and the blood avenger according to these ordinances.

and the blood avenger finds him outside the border of his city of refuge, and the blood avenger kills the manslayer, he will not be guilty of blood