MINNEAPOLIS - The Minnesota Court of Appeals has upheld a serial rapist's conditional release from the Minnesota Sex Offender Program.

The appeals court ruled Monday that a special judicial panel did not err when it granted provisional discharge for Thomas Duvall. The 62-year-old has spent the past 30 years locked up for the violent rapes of teenage girls in the 1970s and 1980s.

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The appeals court found that the state did not meet its burden of proving by "clear and convincing evidence" that Duvall should stay in the sex offender program. Instead, the appellate court said evidence supports the judicial panel's decision to allow his conditional release.

Department of Human Services Commissioner Emily Piper says she has grave concerns about the decision and will exhaust every possible avenue of appeal.