Embattled Chicago Alderman Edward Burke is in more legal hot water after being indicted by a federal grand jury on racketeering, bribery, and attempted extortion charges. An indictment filed yesterday accuses the city’s longest-serving city council member of using his power to extort private legal work from companies and individuals doing business with the city. Two schemes outlined in the indictment involve the old main Chicago post office and the Field Museum. Charges were also handed down to Burke’s top political aide Peter Andrews and developer Charles Cui.