The question of why John Wilkes Booth killed Abraham Lincoln was settled long ago as far as most historians are concerned. Booth in league with a ragtag group of Southern misfits was out to change the outcome of the Civil War. But do we know the full story? This sounds like a question one might hear on a bad TV show about the Kennedy assassination. But it's been raised anew in the aftermath of the publication of the book, Dark Union (John Wiley & Sons, 2003), which claims that a fellow by the name of Boyd was killed in Booth's place at Garrett Farm and that Booth got away. The book, written by Leonard F. Guttridge, an historian, and Ray Neff, a longtime collector of Lincoln documents, utilizes a huge cache of heretofore unexamined documents accumulated through the years by both Neff and Guttridge. They insist that the old story is in error and that we have all been had.

If the documents, which the authors turned over to Indiana State University, are legitimate then Guttridge and Neff are right to believe that the history books have to be rewritten. If the documents are illegitimate then what we have here is one of the great frauds of all time.

So what do have we here? The biggest hoax of our new century (with Guttridge and Neff as its first victims; no one accuses them of manufacturing the documents)? Or a startling, dramatic, and hair-curling discovery?

The opening round in this debate began in January with the publication of"Dark Union: Bad History" by Edward Steers, Jr., and Joan L. Chaconas in the pages of the popular history magazine, North & South.

Shortly thereafter James McPherson, the Civil War historian and a contributing editor at North and South, weighed in against Dark Union, calling the book egregiously in error. He recommended that historians debunk it.

Why should historians be concerned about such fiction passing as history? Precisely because the authors and their publisher repeatedly insist that it is the only true story of the assassination—and thousands of readers will continue to believe them if historians merely ignore or dismiss the book ....

Professor McPherson's comments, appearing in his final column as president of the American Historical Association, drew wide attention.

Next came the counter-attack. David Vancil, the archivist who accepted the documents Neff and Guttridge deposited at Indiana State University, argued in a vigorous piece posted on the web that they are indeed legitimate. He brushed off McPherson's critique.

At HNN's request, Steers and Chaconas then wrote a response to Vancil.

That left just the authors of the book in question to respond. At first, they were reluctant. Neff said any response should be written by Guttridge, who apparently wrote most of the book. But Guttridge indicated he didn't want to stage a defense of the book. The book would speak for itself. He subsequently changed his mind and wrote a lengthy piece taking his critics to task for their unwillingness to countenance a fresh thesis that undermines the"perpetuated story of the Lincoln murder case."

Who's right? You decide.

• Dark Union: Bad History Edward Steers, Jr. and Joan L. Chaconas

• Another Phony Account of Lincoln's Death James McPherson

• Response to James McPherson et al. David Vancil

• Response to David Vancil Edward Steers, Jr. and Joan L. Chaconas

• In Defense of Dark Union Leonard Guttridge
• My Response to Steers & Chaconas and McPherson Ray Neff