In the long foyer of freelance photographer Fred J. Maroon's Georgetown home hangs a line of oversize images from his diverse career. Here is a picture from a fashion shoot in the snow-covered mountains of Afghanistan. There is an artistically depicted bowl of creamy vanilla pudding. Across the wall hang several images of submarines rising out of the ocean like steel dolphins. And in the center of them all there's a black-and-white photograph of scowling, defiant Nixon aide John D. Ehrlichman from July 24, 1973, as he testified at the Senate Watergate hearings. One year after that photo was taken, President Nixon resigned rather than face impeachment, rocking the country.

Along with legions of others, Maroon was there to cover it all. But he had a special place in the process because he knew all the White House players. A few years earlier, in 1970, he had been given White House access to take pictures for a behind-the-scenes book on the Nixon administration. For nine months, Maroon captured the president working solo on speeches, meeting with his inner circle--national security adviser Henry Kissinger, Chief of Staff H.R. Haldeman and domestic policy adviser Ehrlichman--and relaxing with wife Pat in California. Doubleday published "Courage and Hesitation" (with text by Allen Drury) in 1972.

Afterward, Life magazine assigned Maroon to document Nixon's reelection campaign. He started shooting a week after the Watergate break-in. He recalls jokingly saying to deputy campaign director Jeb Magruder, "You guys will do anything for publicity."

In hindsight, his images of two women diligently feeding a shredding machine and campaign staffers listening on headphones in the communications room take on a more ominous meaning. "People wonder, 'Why did they let you keep shooting?' " says Maroon. His best guess is for "a sense of normalcy."

Although Maroon did not have any specific assignments to cover the impeachment hearings on the Hill or Nixon's resignation, he was there, snapping away. "I had to continue to document this wherever it took me," he says. The resulting photographs trace a line from powerful politician to defeated man.

The experience of covering the Nixon White House did not sour Maroon on politics. "I was not a victim of what happened in Watergate," he says. "I was just a messenger." Still, he was shaken when, about a year after Nixon stepped down, some college students in Philadelphia reacted angrily to the pictures during a talk. Feeling his photographs would only stoke the "negative and worrisome mood" of the country, Maroon locked his 576 rolls of film in storage.

A few years ago the photographer, now 75, felt it was time to look at the images again. To coincide with the 25th anniversary of Nixon's resignation, the exhibit "Photographing History: Fred J. Maroon and the Nixon Years, 1970-1974," is on display at the National Museum of American History. Abbeville Press has just issued a book of the images as well, many of which have never been seen by the public.

The book is dedicated to Maroon's four children. "I hope it gives them and others of their generation, as well as generations to follow, a glimpse at the cast of characters who played important roles in this American drama--in what was, up to then, the greatest political tragedy our country has known," Maroon writes in the introduction.

After graduating from high school and serving in the Navy during World War II, he attended Catholic University, where he got a degree in architecture. "I remember coming out of Union Station on the train and seeing the Capitol and thinking I had to be an architect," he says.

He started snapping pictures of his surroundings and soon became editor of the college yearbook, which by coincidence shared a printing press with Life magazine. An editor there saw Maroon's work and offered him a job as a trainee. He spent only a few months at Life's New York office before winning a scholarship to study art in Paris.

He tried to settle into an architecture career when he returned to Washington, but the camera called. His first photograph, a Washington night scene, was published in Look in 1954. Maroon knew he had made it when seven years later the magazine published his eight-page color spread of the Kennedy White House. Although he credits architecture with teaching him many of his camera skills, he never returned to the drawing board.

Although Maroon has returned to the executive mansion a handful of times on assignment, most recently to take photos of the Clinton White House at Christmas, he has shied away from doing another lengthy study of a political figure. After the Nixon years, Maroon took his family on a cross-country trip, to "photograph the positive side of America." That experience turned into "These United States" (with text by Hugh Sidey), published in 1975. One of his current projects is photographing flowers from Washington's botanical gardens in his studio, a far cry from watching a president at work.

Still, Maroon recognizes that the Nixon pictures might be his most important project and is grateful to the former president for allowing him access, even after the Watergate break-in. The photographer thinks he knows why it was granted.

"You've got to give Nixon credit," he says. "I think he always had his eye on history."

Photographing History: Fred J. Maroon and the Nixon Years, 1970-1974, at the National Museum of American History, 12th Street and Constitution Avenue NW, through Dec. 5.