One needn't delve very far into the horrors contained by the Minnesota Sex Offender Program to reach three disturbing conclusions: Some of those people should never be allowed to walk freely in society again; some of them probably should be; and Minnesota has abdicated the responsibility of telling the difference.

Last week's Star Tribune series, by reporter Larry Oakes and photographer Jim Gehrz, told a remarkable and disturbing story about open-ended incarceration. The program serves a legitimate need: Some sexual predators, like other convicts, reach the end of their prison terms having been punished but not reformed. Psychological evaluation suggests they are likely to commit new crimes. Off they go to the sex-offender treatment centers, which are like prisons but much more expensive.

It may not be a perfect solution, but it would be defensible -- if it were used sparingly, on a tightly targeted population, with demonstrably effective treatment programs and a reasonable hope for eventual release. None of those conditions applies.

Since the murder of Dru Sjodin in 2003 and the subsequent conviction of a released sex offender, Alfonso Rodriguez Jr., authorities have resorted to commitment much more often than in earlier years. That fact alone suggests forces at work beyond a dispassionate application of law and science. The population of the centers has grown from 200 in 2003 to more than 500 today. And though the residents are receiving treatment, the effectiveness of that treatment is open to question in light of the number of patients who have been released: none.

If the reports in the Star Tribune prompt a wider discussion and reevaluation of this program, as they should, those doing the discussing and evaluating will have to grapple with some difficult questions. When deciding whether a sex offender may be released, how much risk of re-offense is acceptable? Survivors of victims of violent crime are sometimes shocked by the seemingly short sentences imposed on the perpetrators, some of whom emerge from prison ready to commit new crimes. By what rationale is that risk more tolerable for a killer than for a sex offender? Can the fallible science of risk assessment be strengthened? A senior law-enforcement official pointed out last week that any talk about changing the system will turn finally on one other question: How much risk is the public willing to bear and at what cost?

Dennis Linehan, a sex predator whose crimes helped prompt the sex-offender program, clearly needs to stay confined. Rodriguez, whose crimes helped prompt a wave of new commitments, clearly should have remained confined before he was released and murdered Sjodin. But public policy ought not be driven by the overwhelming public loathing that such predators evoke.

If the state's true intention is to lock such people away for life, let it say so, using the language of laws and due process. Let it search in broad daylight for the means to put away those who must never be free and to help those who may be salvageable, and to become expert in telling them apart.