Very interesting piece. I hadn't considered many of the arguments. One idea I have is to have isolated communities somewhere that people who have been convicted of murder or other serious violent crimes are essentially made to go and live in through ostracism by their fellow citizens. So, in the case of Dylan Roof, communities could pass resolutions barring him from living there, and he would then by necessity have to go and live in one of these isolated communities inhabited solely by the worst criminals. They would be sort of be modern-day leper colonies but for criminals.