Serial killer Dennis Nilsen who butchered 15 men in the 1970s and 1980s before being caught when body parts were found clogging his drain after he COOKED his victims dies in jail aged 72.
Keeping evil alive within our midst has no value, spiritual or otherwise. God loved even Dennis Nilsen - but it was for him to make his peace with God. During a life sentence, it is far easier to feel sorry for yourself rather than sort out your spiritual situation.
With a slight addition to the words of Oscar Wilde, "When a man knows he is going to be hanged in the morning, it concentrates his mind wonderfully [and possibly induces him to examine his soul as he stares into the precipice of imminent eternity and God's wrath.]
I would wager that far more people have turned to God begging for His forgiveness in a death cell than in the main part of any prison.
God sometimes requires us to make tough and, to us, disagreeable decisions. No matter. We have a duty to both God and society.