There's a disturbing story out about presidential historiography, involving our most revered president, Abraham Lincoln.

Thirteen years ago, an amateur historian said he had discovered the pardon of a Union army deserter that Lincoln issued on April 14, 1865 -- the same day of the president's murder at Ford's Theatre.

Yesterday, the National Archives accused that historian, Thomas Lowry, of altering the document that was actually written exactly a year before, in 1864 -- it said Lowry changed the "4" to a "5" with a fountain pen.

Lowry told The Washington Post that federal agents forced him to confess, and he denied wrongdoing: "I consider these records sacred. ... It is entirely out of character for me. I'm a man of honor."

David S. Ferriero, archivist of the United States, told the Post that the Archives were familiar with Lowry and his wife, frequent visitors to the document rooms.

"It's horrible," he said. "This is a situation of having instilled a lot of trust in a regular user and not being suspicious."

Lowry has now been banned for life from the National Archives.