A researcher retained secretly by the chairman of the Corporation for Public Broadcasting, to monitor the "Now" program with Bill Moyers for political objectivity last year, worked for 20 years at a journalism center founded by the American Conservative Union and a conservative columnist, an official at the journalism center said on Monday. The decision by the chairman, Kenneth Y. Tomlinson, to retain the researcher, Fred Mann, without the knowledge of the corporation's board, to report on the political leanings of the guests of "Now" is one of several issues under investigation by the corporation's inspector general. At the request...