A chance request in 2004 for a 19th-century German book about the Mississippi River was what alerted the National Library of Sweden that dozens of rare books from its collection had been stolen. Now that volume and another valuable antique book that contains early maps of America have been recovered and are being returned to library officials at a ceremony on Wednesday at the office of the United States Attorney in Manhattan. These books were part of sensational heist engineered by Anders Burius, a senior librarian dubbed the “Royal Library Man,” who committed suicide shortly after his arrest nine years ago. A crack in the case first came last year after a rare atlas from 1597 was recovered. Mr. Burius sold or consigned at least 13 of the books to Ketterer Kunst, a German auction house....