MINNEAPOLIS (AP) — Human Services Commissioner Emily Piper says she'll appeal a judicial panel's approval of the conditional release of a serial rapist from the Minnesota Sex Offender Program.

Thomas R. Duvall has spent the past 30 years locked up for the violent rapes of teenage girls in the 1970s and 1980s. The Star Tribune reports that a three-judge panel on Monday approved Duvall's provisional discharge, saying his progress in treatment outweighs his diagnosis as a sexual sadist.

But Piper said in a statement Tuesday that she believes Duvall poses an "exceptional risk" to public safety and should not be released.

Duvall's case sparked a firestorm four years ago when MSOP staffers recommended his conditional release. Attorney General Lori Swanson and other officials objected, and Duvall withdrew his petition.

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