After White’s article was published, demands rose for full disclosure. The next month, White’s colleague at the Providence paper, Joseph Ungaro, asked Nixon about his taxes during his appearance at a newspaper editors’ conference in Florida. Nixon replied: “I welcome this kind of examination, because people have got to know whether or not their president is a crook. Well, I am not a crook.”

No single comment would stick more firmly to Nixon. It had never before been necessary for a president to distinguish himself from ordinary tax cheats. Yet still he wouldn’t release his taxes.

In the meantime, the I.R.S. reversed itself and decided to audit Nixon’s returns for the previous few years. While the audit was underway, Nixon buckled to public pressure in December 1973 and released five years of tax documents. He also asked a congressional committee to review, among other things, his gift of the papers.

The aftermath was sweeter for White than for Nixon. In May 1974, White won a Pulitzer Prize for his reporting. He died in 2005 without revealing his source. (As the story unfolded, I.R.S investigators said they had solved the mystery of the leak by tracing the president’s tax records to a photocopy machine in the agency’s national computer center in Martinsburg, W.Va. One unidentified I.R.S. employee quit to avoid being fired.)