Numbers 35:27-31 New King James Version (NKJV)

27. and the avenger of blood finds him outside the limits of his city of refuge, and the avenger of blood kills the manslayer, he shall not be guilty of blood,

28. because he should have remained in his city of refuge until the death of the high priest. But after the death of the high priest the manslayer may return to the land of his possession.

29. ‘And these things shall be a statute of judgment to you throughout your generations in all your dwellings.

30. Whoever kills a person, the murderer shall be put to death on the testimony of witnesses; but one witness is not sufficient testimony against a person for the death penalty.

31. Moreover you shall take no ransom for the life of a murderer who is guilty of death, but he shall surely be put to death.

Numbers 35