So what should we do with serial killers, pedophiles, rapists, etc? Let them live among us?
Justice and restitution (if possible) should be proportionate to the crime. Forcing disinterested parties or worse, the surviving members of the victims family, to pay to house a murderer is a crime in and of itself. So I don't think life in prison solves anything if it is paid for by disinterested parties.
Dylan Roof could be exiled. He could be forced to labor to pay for his upkeep and the surviving victims (children of the people he killed etc.) and then set free or then killed.
He could be executed summarily. He could be forgiven. It's not a "we" choice though. The decision should be the domain of those victimized, or closest to the victims, it's not up to me. If he had murdered a loved one of mine, I'd have a hard time forgiving him.