Prosecutors in St. Paul vacated a 1985 rape conviction yesterday after a review of old cases led to DNA testing that showed they had the wrong man.  It is believed to be the first time that a prosecution-initiated review, as opposed to a defendant's appeals has resulted in exoneration.

"This sends a strong message that our No. 1 concern is justice," said Susan Gaertner, the Ramsey County attorney, whose office spent 18 months studying 116 pre-1995 convictions to see if new technology might change the outcome.  "I'm not proud that we goofed, but I'm proud that we welcomed the light to be shown on our prior cases, that we were willing to use DNA evidence to possibly disturb convictions we'd obtained."

The man convicted of the rape, David Brian Sutherlin, is serving a life sentence for a double murder committed while he was out on bail on the rape charge.  Prosecutors expect the lifting of the rape conviction to ease his path to parole, for which he became eligible this year.

DNA testing also identified the actual rapist, though a statute of limitations prevents his prosecution; Ms. Gaertner declined to identify the man, but said she would try to force his registration as a sex offender.

With defense requests for DNA testing having led to more than 100 exonera-tions, Ramsy County is one of at least a half-dozen where prosecutors conducted a wholesale review of old convictions.  The San Diego district attorney's office, the first to undertake such a project, has looked at more than 700 cases, though prosecutors there, as in St. Paul, decided that only a few merited DNA testing.

Ms. Gaertner wanted to conduct DNA tests in 3 of the 116 cases, but physical evidence in 2 of them had been destroyed.  In vacating the charges against Mr. Sutherlin, 40, Ms. Gaertner called on law enforcement agencies to adopt policies requiring the retention of evidence as long as defendants are incarcerated or crimes remain unsolved.

Defense lawyers have criticized the prosecutorial reviews, saying that the criteria imposed are too narrow - excluding, for example, defendants who pleaded guilty or confessed.  About a quarter of the exonerations nationally have involved false confessions.

Peter J. Neufeld, co-director of the Innocence Project at the Benjamin N. Cardozo School of Law in Manhattan, said that once a prosecutor had reviewed a case and determined DNA testing to be unwarranted, defendants might have a more difficult time gaining access to the technology.

"Defense attorneys actually have an interest in exonerating people - prosecutors don't share that interest," Mr. Neufeld said.  "The reason they don't want to go there is twofold; It's obviously embarrassing, but it will also precipitate an investigation into the cause of the wrongful conviction.  It's not just one man that is exonerated, you are calling into question hundreds of convictions."

David Gill, Mr. Sutherlin's lawyer, said his client was lucky that the victim's clothing had been saved.

"There are many people in that 117 or whatever they reviewed that are innocent," Mr. Gill said, "it's just that they don't have the benefit of the right evidence being left at the scene or being preserved.  He gets the big cigar; they don't."

Ms. Gaertner, who was elected in 1994 and decided to conduct the review after a national meeting of prosecutors last year with former Attorney General Janet Reno, said her office did not ignore cases in which there had been confessions.  The vast majority of the 116 under review, she said, either had strong corroborating evidence or did not turn on questions of identity that could be resolved by DNA.  Pointing out that Mr. Sutherlin had not requested DNA testing and would not have been exonerated without the prosecutorial effort, Ms. Gaertner invited defense lawyers to review the 116 files.

"The major reason we undertook this review is because of the attack on prosecutors and the criminal justice system lately - I'm afraid that it's left an impression with the public that all we care about is convictions, and not justice," she said.  "If by standing up and saying we goofed that enhances their confidence that in other cases we haven't goofed, that accomplishes something."