Works of art stolen by the Nazis from a renowned Austrian-Jewish cabaret performer more than 80 years ago were officially returned to his heirs Wednesday at a ceremony in the Manhattan district attorney’s office. The seven drawings, collectively valued at nearly $10 million, were among dozens of artworks by late Austrian artist Egon Schiele seized in 1938 from Fritz Grünbaum, an avid art collector who died at Germany’s Dachau concentration camp during World War II. While most of Schiele’s work was sold off to help finance the German war machine, the whereabouts of the seven drawings were unknown until they...