The New Testament makes the Ten Commandments look easy.
For you as a person
Matthew 6:14-15: “For if you forgive other people when they sin against you, your heavenly Father will also forgive you. But if you do not forgive others their sins, your Father will not forgive your sins.”
Colossians 3:13: “Bear with each other and forgive one another if any of you has a grievance against someone. Forgive as the Lord forgave you.”
Romans 12:19-21: “Do not take revenge, my dear friends, but leave room for God’s wrath, for it is written: ‘It is mine to avenge; I will repay,’ says the Lord… Do not be overcome by evil, but overcome evil with good.”
For the state
Romans 13:1-4: “Let everyone be subject to the governing authorities, for there is no authority except that which God has established… For the one in authority is God’s servant for your good. But if you do wrong, be afraid, for rulers do not bear the sword for no reason. They are God’s servants, agents of wrath to bring punishment on the wrongdoer.”
1 Peter 2:13-14: “Submit yourselves for the Lord’s sake to every human authority… who are sent by him to punish those who do wrong and to commend those who do right.”
Forgiving a murderer is an act of obedience, not a denial of the crime’s severity.