March 9 (UPI) -- Alexander Butterfield, the aide to former President Richard Nixon who revealed to Congress the secret taping system in the White House that captured recordings about the Watergate burglary, died on Monday at age 99. Butterfield's testimony before the Senate Watergate Committee that Nixon had recorded conversations in the White House, and the recordings that were eventually revealed, led to Nixon's resignation from office over the burglary scandal. His death was confirmed to