"Therefore, however Magistrates might connive at the crime – God from other quarters sends executioners who shall render unto sanguinary men their reward. God so threatens…, that He even arms the Magistrate with the sword for avenging of slaughter."
Calvin also remarks4 that precisely because God "forbids killing" – it follows that "murderers may not go unpunished." For the Lord God Jehovah "the Lawgiver Himself puts into the hands of His [politico-governmental] Ministers – a sword to be drawn against all murderers" and other capital criminals. Cf. Romans 13:1-14.