Actually, in Biblical Ethics, "preventing murder" is generally left to individual self-defense. If the individual succeeds in preventing a murder (even by killing the presumptive murderer), there's generally no cause for Government Action.
However, in any case -- "Murder" is NOT Biblically defined as "permitting death to naturally occur". That just isn't Murder, according to any verse anywhere in the Bible.
King David finagled to let Uriah be killed, and God didn’t let him off the hook... God hit David right between the eyebrows through the prophet Nathan as “YOU killed Uriah through the enemy.”
Such sophistry is frowned upon by the Lord.