WASHINGTON — Neil Sheehan, a reporter and Pulitzer Prize-winning author who broke the story of the Pentagon Papers for The New York Times and who chronicled the deception at the heart of the Vietnam War in his epic book about the conflict, died Thursday. He was 84.

Sheehan died of complications from Parkinson’s disease.

His account of the Vietnam War, “A Bright Shining Lie: John Paul Vann and America in Vietnam,” took him 15 years to write. The 1988 book won the Pulitzer Prize for nonfiction.

Sheehan served as a war correspondent for United Press International and then the Times in the early days of U.S. involvement in the Vietnam War in the 1960s. It was there that he developed a fascination with what he would call “our first war in vain” where “people were dying for nothing.”

As a writer for the Times based in Washington, Sheehan was the first to obtain the Pentagon Papers, a history of U.S. involvement in Vietnam ordered up by the Defense Department. Daniel Ellsberg, a former consultant to the Defense Department who had previously leaked Vietnam-related documents to Sheehan, had allowed the reporter to see them.