Robert Heiss sat in his West Side fast-food restaurant and swore he simply found the thing--a $175,000 viola owned by the Chicago Symphony Orchestra--on the sidewalk and had no idea who owned it or what it was worth.

    "I didn't know the Chicago Symphony owned it.   I'm just a chef.  I don't know these things.  I threw it in my closet," said Hess, 71.  "For that they locked my up and treated me like a dog."

    It might now be that simple, however, which is why Heiss spent two nights in Cook County Jail last week and could wind up in prison.

    It's a case that illuminates one of the most basic laws of civil behavior--that finders aren't necessarily keepers.

    The story began in September, 1996, when a CSO violist told police he accidentally left the instrument on the sidewalk as he was loading his car, only to find it missing moments later when he rushed back to the parking spot after realizing his mistake.

That was on Columbus Drive, where Heiss said he was walking back from the Columbus Yacht Club, where he had met a friend.

    "It was sitting there in a beat-up case," Heiss said.

    The case was clearly marked property of the Chicago Symphony Orchestra, said Cliss Seward, an investigator hired by the Hartford Insurance Co. to investigate the $175,000 claim the company paid to the CSO.

    Seward put ads about the missing instrument in Chicago area newspapers, including the Sun-Times. And the CSO alerted area music shops.

    Heiss, meanwhile, claimed he researched violins and violas on the internet, where he discovered the name of Fritz Reuter, a Lincolnwood expert on the instruments.

    "I went to him because I didn't know what I had," Heiss said.

 Police say Heiss went to Reuter to have the instrument appraised with the idea of selling it on consignment.  Reuter, who was familiar with the alert for the missing viola, contacted authorities, who asked Heiss to come in for questioning.  He did, and eventually was arrested and charged with felony theft.

    "If you knowingly don't return property to someone, it is a misdemeanor," a source close to the case said. "If you try to sell it, it becomes a felony."

    Heiss, meanwhile, claimed to have been told the viola is a fake, that it is not a 1723 Montagnana worth $175,000, but a 19th century instrument worth a fraction of that.

    Tom Hallett, chief financial officer of Chicago Symphony Orchestra, said officials are aware of the dispute over the instrument's origins, and they have received appraisals both above and below $175,000. But since the CSO has no intention of selling it, the question is somewhat moot, other than in how it affects the premiums paid for insurance.

    As for the $175,000 insurance claim paid two years ago, it already has been paid back.