A media executive who was a key player in the evolution of Tribune Co. has died. The Washington Post reports that Stanton Cook died Sept. 3 at his home in the Chicago area. He was 90.

As CEO and president of the company, Cook “molded Tribune Co. into a modern, diversified media corporation that broke with its conservative past by calling for the resignation of President Richard Nixon, bought a Major League Baseball team and established itself as the largest operator of independent TV stations in the United States,” the paper reports.

Cooks cause of death was not revealed.

“Mr. Cook joined the Tribune as an engineer in the newspaper’s production department and rose through the ranks. He became general manager in 1970 and was elected president of the newspaper and a director of the parent company in 1972. In 1973, he became publisher of the Tribune and a vice president of the parent company,” The Post reports.

Cook was at the helm as the paper moved away from its traditional Republican bias, the report notes.

“In May 1974, about a month into Mr. Cook’s job as Tribune Co. chief executive and president, he backed an editorial that called for Nixon to resign amid the unfolding Watergate scandal,” the story reports, adding: “The Tribune editorial came a week after the Tribune became the first to publish the entire Watergate-related transcripts from Nixon’s scandal-plagued White House. In one day, the Tribune produced a 44-page special section that included the transcripts, an effort that TV commentator John Chancellor called at the time ‘a publishing miracle.’”