Fred D. Thompson rose to national prominence in the mid-1970s. As chief counsel to the Republicans on the Senate Watergate Committee, he famously asked the question that revealed the existence of the White House taping system that ultimately led to President Richard M. Nixon's resignation. But Mr. Thompson was also an active participant in the White House's efforts to deflect blame from the president and discredit his accusers, plotting strategy with Mr. Nixon's lawyers and leaking information to them. (Continued for 9 more pages)