Numbers 35:30-34

30‘If anyone kills a person [intentionally], the murderer shall be put to death on the testimony of [two or more] witnesses; but no one shall be put to death on the testimony of [only] one witness.

31Moreover, you shall not accept a ransom [in exchange] for the life of a murderer guilty and sentenced to death; but he shall certainly be put to death.

32You shall not accept a ransom for him who has escaped to his city of refuge, so that he may return to live in his [own] land before the death of the high priest.

33So you shall not pollute and defile the land in which you live; for [the shedding of innocent] blood pollutes and defiles the land. No atonement (expiation) can be made for the land for the [innocent] blood shed in it, except by the blood (execution) of him who shed it.

34You shall not defile the land in which you live, in the midst of which I live, for I, the Lord, live among the people of Israel.’ ”