Nauseous and Mad

From an AP story about the horrific Idaho case:

Duncan had spent more than a decade in prison for sexually assaulting a 14-year-old boy at gunpoint in Tacoma, Wash., and was a fugitive at the time of his arrest after he was charged with molesting a 6-year-old boy in Minnesota.

He was released on $15,000 bail earlier this year after being charged with molesting the boy. Police in Fargo, N.D., had been looking for Duncan since May, when he failed to check in with a probation agent.

Link.

We know molesters almost always revert to their crimes, and we know probation doesn't work. Why won't we acknowledge it and keep these "people" locked up for good? How many children must be molested in obeisance to the therapeutic society that thinks it can cure everything? How many cases of molestation could we stop if we just kept these demon-possessed people chained?