ST. LOUIS.- The burial mask of Ka Nefer Nefer, which is at the St. Louis Art Museum, should be returned on Monday to Egyptian authorities. The deadline the 3,200-year-old mummy mask has won´t be met by the museum unless it gets more proof that it belongs to Egypt, Museum Director Brent Benjamin said Friday. "Zahi Hawass, Secretary General for the Supreme Council of Antiquities in Egypt, said the mummy mask probably was stolen before the museum obtained it in 1998 and has threatened to turn the dispute over to authorities", reported the Detroit Free Press. The woman's burial cover made of wood and plaster with glass eyes was excavated from a pyramid in 1952 in Saqqara, Egypt.