Bill O’Reilly (Frank Micelotta/Associated Press)

Killing Reagan,” the fifth in the murderous series penned by Fox News host Bill O’Reilly and co-author Martin Dugard, was published a month ago. Yet Dugard just yesterday sent an inquiry to the Ronald Reagan Presidential Library seeking a key document for a central contention in the book:

The date on the request was Oct. 19.

The document relates to what O’Reilly himself called the “key part of the book” in a C-SPAN interview with Reaganite Bay Buchanan. The time frame was early 1987, and White House aide James Cannon was formulating a report surfacing concerns from White House aides about the 40th president’s fitness to discharge his duties. The resulting memo was dated March 1, 1987. Though the episode is discussed in O’Reilly’s book, it isn’t new: A 1988 book — “Landslide” — by Jane Mayer and Doyle McManus described the report and detailed the staffers’ misgivings: “They told stories about how inattentive and inept the President was. He was lazy; he wasn’t interested in the job. They said he wouldn’t read the papers they gave him — even short position papers and documents. They said he wouldn’t come over to work — all he wanted to do was to watch movies and television at the residence.”

In any case, the memo prompted Chief of Staff Howard Baker and others to scrutinize Reagan’s behavior in a March 2, 1987, meeting. They found him highly fit.

After news of the Cannon inquiry surfaced, the White House dismissed it as relying on disgruntled loyalists of Donald T. Regan, who had been replaced as chief of staff in February 1987. “Everyone knew when Regan left they were all leaving, and they all were gone within weeks,” presidential spokesman Marlin Fitzwater said of that crowd.

Melissa Giller, a spokeswoman for the Ronald Reagan Presidential Foundation, confirms Dugard’s tardy request for the Cannon memo. O’Reilly, notes Giller, has boasted that “all the facts in his book have been sourced by multiple people or sources — that’s there’s truth behind their facts. It is suspicious that they’re now e-mailing us a month after their book is out to ask for an actual copy of the memo.” The memo itself is not in the Reagan Library’s archives, to the best of Giller’s knowledge.

Dugard’s post-publication request for documentary material aligns with the hurry-up-and-publish ethos of Bill O’Reilly Inc. Each year, O’Reilly and Dugard pump out one of these best-selling “Killing” volumes, which are powered by research, a fast-paced present-tense narration and storytelling monotony.

In his broadcast last night, O’Reilly lashed out at the critics — he called them Reagan “guardians” — who’d taken issue with various factual and thematic aspects of “Killing Reagan.” He even singled out Christopher Cox, a former White House counsel under Reagan as well as an eventual chairman of the Securities and Exchange Commission, and former California Gov. Pete Wilson for “warning” the authors against publishing negative stuff about Reagan.

In an interview with the Erik Wemple Blog, Cox denied any such scenario. It was Dugard who requested “help in researching the book,” recalls Cox. “In order to help, I introduced him to Reagan scholars.” Those scholars, continues Cox, concluded that the publication deadline didn’t leave enough time to properly address issues in the manuscript. “The interests of the Reagan scholars was in accuracy only. There was never any admonition about merely negative things,” says Cox.