What White House Official provided additional testimony against Nixon, including tape recordings?

Alexander Butterfield, a White House aide, revealed that Nixon had a secret taping system and provided testimony that led to the tapes becoming central evidence. Archibald Cox was the special prosecutor, John Dean was a former White House counsel who testified against Nixon, and Carl Bernstein was a journalist. The correct choice is Alexander Butterfield.

AI-written and checked against the verified answer.