Whatever you think of de Sade, he was a complex figure and we should not look for easy answers with him. He was, strangely perhaps, against the death penalty, and he was never put in prison for murders or anything like that.
In a civilized society, all crimes are likely to be sins, but most sins are not and ought not to be treated as crimes.
What restrains us from killing is partly fear of punishment, partly moral scruple, and partly what may be described as a sense of humor.
They're not supposed to show prison films in prison. Especially ones that are about escaping.
The perfection of a thing consists in its essence; there are perfect criminals, as there are men of perfect probity.