It is generally recognized that the government has the power of the sword, in warfare and capital punishment, which does not violate the sixth commandment against murder.
a Brakel, the Dutch Reformation minister notes the Anabaptist objection: "having had a bad experience at Munster [!]... they advance Matthew 5:39-40, 44: [turn the other cheek... resist not evil]. These texts do not refer to the work of civil authorities, for they have been commanded to do so.... The Lord Jesus speaks of private individuals... of taking the sword and not of receiving the sword form God (Rom 13:4)."
That last turn of phrase made me think of the zealots, who spoke of themselves as having taken up the sword. I believe the crusaders spoke this way, too. I'm not saying all zealots and crusaders were murderers, but they were misguided in their use of the sword. It would be like a soldier in an unjust war, who really thinks he is doing right. What category of sin or evil is that?
Once again we see the ditch on both sides of God's road. The left ditch of no resistance - pacifism as a government. Unilateral disarmament and all that. Romans 13 speaks against this. The right ditch of taking up the sword in righteous indignation against a real evil, where there is no authority to do so. Jesus speaks against this in telling Peter to put his sword away, in Gethsemane.