2 Plead Not Guilty in Trade Secret Theft for China Two suspects have pleaded not guilty to federal charges that they stole DuPont Co.'s technology and sold it to a company controlled by the Chinese government. Robert Maegerle and Christina Liew entered their pleas Thursday to economic spying charges. Liew is married to Walter Liew, the central figure in a sprawling case involving the recipe for a chemical whitener that's become a $17 billion-a-year industry. Walter Liew's arraignment was postponed two weeks to conduct a search for lawyers. He remains in custody. The Chinese government-controlled company, Pangang Group Co. Ltd., and two other men also are charged with stealing the secrets for titanium oxide. Longtime DuPont scientist Tze Chao already has pleaded guilty and is cooperating with authorities. A fifth man is at large and believed to be in China.