Serious answer to your question in this link
http://www.christianbiblereference.org/faq_CapitalPunishment.htm
My own personal view is that since Almighty God is perfect Justice and forbids the taking of innocent Human Life...according to the way he corrects Evil with its own Evil we can assume he will punish murder with murder..but since he is Spirit, we are talking permanent Spiritual Death.
There is one caveat, since we all have the chance to be forgiven for confessing our Sins and believing on Christ, Almighty God will NOT hold even murderers accountable if they repent from their Sin. Remember, Almighty God is 1st Holy and then Just, but he is also Merciful, and he forgives ALL Sins...even murder! But one MUST repent, and ask for forgiveness believing on Christ that all Sins are forgiven never to be remembered.
So while the Bible does not specifically call for Capital punishment after Christ, Almighty God is just, and does forbid murder. He will correct murder as he once did in the Old Testament before Christ's work at Calvary, and he requires Justice so his ultimate punishment for murder without repentance is Spiritual Death. Our physical Laws in some cases also call for p
hysical death in certain instances of Murder, and that is consistent with how Almighty God deals with Evil. And eye for an eye.
Matthew 5: 3-8
"You have heard the law that says the punishment must match the injury: 'An eye for an eye, and a tooth for a tooth.'
Christ further admonishes us in that passage not to retaliate, but to be slow to anger, and let Almighty God be the ultimate Judge of ultimate Justice. However as I said, crime does NOT go unpunished, and in some cases perfect Justice for murder involves removing that Life to correct the injustice in
this World which Almighty God both ordains and commands.
Zechariah 7:9
Then the word of the LORD came to Zechariah, saying, 9
“This is what the LORD of Hosts says:‘Administer TRUE justice. Show loving devotion and compassion to one another. 10 Do not oppress the widow or the fatherless, the foreigner or the poor. And do not plot evil in your hearts against one another.’…
Hope that answers...read the link...lots more in there.