Richard Nixon actually said...
As a mark of respect to the memory of J. Edgar Hoover, it is hereby ordered, pursuant to the provisions of Section 4 of Proclamation 3044 of March 1, 1954, as amended, that until interment the flag of the United States shall be flown at half-staff on all buildings, grounds and naval vessels of the Federal Government in the District of Columbia and throughout the United States and its Territories and possessions.
Context
Executive Order 11669—J. Edgar Hoover
05/01/1972