The original ground-breaking article is now available in multiple formats:

The Washingtonian

November 1980, pp. 157-192.

There Were Two Conspiracies in the Kennedy Assassination: The First Was to Murder the President. The Second Was to Pretend There Was a Full and Complete Investigation.
This Is the Story of Government Investigator Gaeton Fonzi and His Three-Year Search for the Truth, His Efforts to Track Down a Mysterious American Spymaster Seen in Dallas with Lee Harvey Oswald in September 1963, His Work for the House Assassinations Committee That Was Supposed to Tell the American People What Really Happened on November 22, 1963.
Fed Up with the Politicizing of This Last Investigation, He Breaks His Oath of Silence to Tell What the Insiders Know About the Assassination of President John F. Kennedy. It Is a Suspenseful Spy Story, It Is a Clear-Eyed Account of How Washington Handles Serious Issues, and It Is History.

Read complete Who Killed JFK? article.

The book this article was expanded into was aptly titled, The Last Investigation.

See Also: Original Manuscript of The Last Investigation.