The state can not deal with them until after they do their killing, often after numerous killing, because they often don't get caught.
Time was when we had confidence in law enforcement and they could tell such skum never to appear again in their community. (And they could enforce it with unfortunate accidents for slow-learning punks.)
Now we have these sociopaths protected by a huge, anti-law enforcement coaliton (ACLU and such) that thinks the cops are the criminals.
The day could come would citizens would revert to an older time when they took their protection in their own hands. Vigilante justice is very rough (approximate) justice and a huge step backward for civilization. But I, personally, would not be unsympathetic toward undoucmented lawmen who could take one look at such characters and have all the probable cause they needed to start the justice process.
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