As most people are posting here, murder and capital punishment are two different things. In fact, the penalty for murder IS capital punishment. Did Jesus have something to say about it? Yes, Jesus said a man was better off having a millstone tied about his neck and cast into the sea than to cause harm to a child.
There are a few other instances in the New Testament (see scriptures below) that verify how God put ruling authorities in place to keep society safe from those who have no fear of God.
Luke 17:1,2, Then He (Jesus) said to the disciples, “It is impossible that no offenses should come, but woe to him through whom they do come! 2 It would be better for him if a
millstone were hung around his neck, and he were thrown into the sea, than that he should offend one of these little ones."
Romans 13:1-4, "Let every person be in subjection to the governing authorities. For there is no authority except from God, and those which exist are established by God. 2 Therefore he who resists authority has opposed the ordinance of God; and they who have opposed will receive condemnation upon themselves. 3 For rulers are not a cause of fear for good behavior, but for evil. Do you want to have no fear of authority? Do what is good, and you will have praise from the same; 4 for it is a minister of God to you for good. But if you do what is evil, be afraid; for it does not
bear the sword for nothing; for it is a minister of God,
an avenger who brings wrath upon the one who practices evil."
Acts 25:10-11, "But Paul said, “I am standing before Caesar’s tribunal, where I ought to be tried. I have done no wrong to the Jews, as you also very well know. 11 “If, then, I am a wrongdoer and have
committed anything worthy of death, I do not refuse to die; but if none of those things is true of which these men accuse me, no one can hand me over to them. I appeal to Caesar.”