Fifty years after the Watergate burglary that led to the downfall of US president Richard Nixon, Washington Post reporter Bob Woodward is still haunted by one question.
"The unanswered question that pulses through all of this is 'Why?' Woodward said at an event at Post headquarters with his former reporting colleague Carl Bernstein.
Why did top members of Nixon's re-election committee organize a break-in at the Democratic National Committee headquarters at the Watergate on June 17, 1972?
Nixon had won the White House in 1968, the 79-year-old Woodward noted, and was cruising to what looked like another certain victory in the 1972 election.
"He had the brass ring," Woodward said of Nixon, who resigned in 1974 rather than face impeachment over a cover-up of the burglary.
"And so what is the psychology — which I think we never cracked really — of somebody who's attained their goal and fails to ask the question ... What do the people need?
"For Nixon, it really didn't come up," he said.
Woodward and Bernstein praised the late Washington Post publisher Katharine Graham for the support she gave them while reporting the Watergate story.
The 78-year-old Bernstein recounted a visit to the paper one day by someone bearing a subpoena to seize his notes.
Managing editor Ben Bradlee went to see Graham and came back five minutes later, he said.
"And he says, 'Katharine says they're not your notes. They're her notes. And if anybody's going to go to jail, it's her,'" Bernstein recalled.
"To me, it's one of the historic moments in American journalism history," he said.
Woodward said the pair received a note from Graham after Nixon resigned warning them to keep their feet on the ground.
"It said 'Dear Carl and Bob, now that Nixon has resigned, you did some of the stories, fine.
"'Don't start thinking of yourself too highly'," Woodward quoted the note as saying. "'Let me give you some advise and the advise is 'Beware the demon pomposity.'"
- 'Are you dumb?' -
Woodward and Bernstein also recalled encounters with Mark Felt, the FBI deputy director whose identity as the source famously codenamed "Deep Throat" was revealed decades later.
They said Felt was constantly pushing them to look beyond the Watergate burglary to a more wide-ranging conspiracy.
"It was kind of like 'Don't you understand what you have here? This is not just the Watergate burglary, it's dirty tricks'," Woodward said.
"Mark Felt kind of laid it out and said, 'No, this is a much bigger thing. Are you dumb?'"
Artifacts from the Watergate break-in and the newspaper's coverage were on display during the event at the Post's new glittering headquarters in downtown Washington.
Clips were shown from the 1976 movie "All the President's Men" starring Robert Redford as Woodward and Dustin Hoffman as Bernstein.
The artifacts included a door latch from the Watergate which had been covered by a piece of tape by the burglars and was spotted by an alert security guard — a key step in the plot coming to light.
Woodward said it had been purchased at auction by Amazon founder Jeff Bezos, the owner of the Post.
"We're trying to find out how much Bezos paid," he said.