 From 1979 to 1981, he was managing editor of "GEO".Christopher served as the secretary of Pulitzer Prize Board and administrator of the Prizes at Columbia University (where he also taught as an adjunct professor of journalism) from 1981 until his death.He was the first Prize administrator to be recruited directly from the profession; both his immediate predecessor (Richard T. Baker) and the inaugural secretary (John Hohenberg) were already tenured members of the faculty of the Columbia University Graduate School of Journalism upon assuming the post.