Minnesota Attorney General Lori Swanson appears to have won a significant legal victory in her effort to prevent the release of a serial rapist who committed a string of horrific sexual assaults against teenage girls in the 1970s and 1980s.

At a hearing Friday before a state Supreme Court appeals panel, attorneys representing the state, Hennepin County and convicted rapist Thomas Duvall, 58, did not challenge Swanson's court motion for a formal public hearing on the proposal to grant Duvall supervised discharge from the Minnesota Sex Offender Program (MSOP).

Though no ruling was issued Friday, the absence of legal opposition makes it almost certain that Duvall will not be released until several experts and some of his victims get an opportunity to testify against his release before the appeals panel, which reviews proposed discharges. A five-day hearing has tentatively been scheduled for early April.

"Duvall's many victims should also have the opportunity to express their viewpoints," said State Solicitor General Alan Gilbert during Friday's hearing. "Transparency is essential in a matter of this importance to the public and public safety."

Duvall, who did not appear at Friday's hearing, has been convicted on three separate occasions of sexually assaulting teenage girls — each time shortly after he was released from prison.

Victims sat in courtroom

In one particularly horrific assault in 1987, Duvall tied up his victim with an electrical cord and then raped her repeatedly while hitting her with a hammer.

At least four of Duvall's victims and their relatives sat in the second row of the courtroom Friday, staring hard as attorneys discussed whether Duvall had shown enough progress in treatment to be released without posing a risk to the public.

At the conclusion, one of the victims expressed relief that experts would review the case again before Duvall's release. "We need to know what's going on with [Duvall], with his mind," said the victim, who declined to reveal her name for safety reasons. "I just can't believe he's ready."

The debate over Duvall's release comes as state officials consider broad changes to the state's controversial system of committing some of Minnesota's most violent sex offenders to indefinite high-security confinement after they have completed their prison sentences.

With some 700 offenders confined in the MSOP, sex offenders and their advocates say civil commitment amounts to a de facto life sentence because almost no one has ever been released.

A 15-member task force of judges, lawmakers and mental health and legal experts is considering several reforms, with a report due Dec. 1.

Passions reignited

Others, including Rep. Tony Cornish, R-Vernon Center, and Hennepin County Attorney Mike Freeman have argued for scrapping civil commitment entirely in favor of harsher prison sentences and treatment in prison.

The debate over Duvall's release has reignited political passions that have long flickered around the issue.

On Friday, Rep. Kurt Zellers, a former state House speaker and a candidate for governor, called the proposed release "arbitrary and capricious" in a letter to Swanson's office. "One of the hockey moms said to me at practice on Sunday, 'Why the hell would the governor let this guy out?' " Zellers said.

Hours later, Gov. Mark Dayton's office fired back, releasing a statement calling on Zellers to "finally do what he neglected to do as speaker: pitch in and help find a better solution to this extremely difficult problem."

Speaking after the hearing Friday, Assistant Hennepin County Attorney George Widseth expressed concern that Duvall's release had already become overly politicized and might get in the way of sound judgment.

"Yes, Duvall has a horrendous history, but so does everyone else in the [state sex offender] program," Widseth said. "The question is not, 'Did he commit horrible crimes?' The question is, 'How well has he been doing in treatment and is he ready to come out?' "