Bobby Chen achieved the rarest of legal feats: Although he had no lawyer, he persuaded the U.S. Supreme Court to hear his case. Chen had sued Baltimore, alleging the city illegally razed his rowhouse in 2008 to conceal property damage caused by the demolition of a city-owned house next door. But now the court can’t find Chen, and lawyers seeking to help him don’t know how to reach him. Baltimore officials haven’t heard from him either. It is a high-court mystery seemingly without modern precedent, and it has court officials scratching their heads. There are few clues about where Chen might be. He provided the court with no phone number. The email address he listed was a Yahoo account that has been disabled. Someone at the Flushing, New York, address where he’d indicated that he lived and worked said Chen moved months ago. Meanwhile, the clock is ticking: Chen’s main brief is due Dec. 22.