If you yourself disobey God's word,  what do you think that your own fate will be??   For you to defend sin, risks damnation on your eternal soul.

Read (Exodus 21: 23 - 25]:  "23.And if any injury occurs, then you shall give life for life, 24. Eye for eye, tooth for tooth, hand for hand, foot for foot, 25. Burning for burning, wound for wound, stripe for stripe."

That is the fate that this killer clearly deserves.