Lyndon B. Johnson hoped that the Warren Commission would convince the American people that President John F. Kennedy had been killed by a single gunman, Lee Harvey Oswald. However, public opinion polls suggested that ever since the publication of the report the vast majority of the adult population believed that he died as a result of a conspiracy.
These numbers increased during the investigations of Frank Church and his House Select Committee on Intelligence Activities (HSCA). This was followed by the House Select Committee on Assassinations. As a result of this acoustic evidence G. Robert Blakey , the HSCA's chief counsel was able to state that there were "four shots, over a total period of 7.91 seconds were fired at the Presidential limousine. The first, second and fourth came from the Depository; the third from the Grassy Knoll."
The HSCA concluded that "scientific acoustical evidence establishes a high probability that two gunmen fired at President John F. Kennedy." It added that on the basis of the evidence available to it, that President John F. Kennedy was probably assassinated as a result of a conspiracy. The committee is unable to identify the other gunman or the extent of the conspiracy."
The American public continued to believe that the full story of the assassination of John F. Kennedy had not been told. This feeling was increased with the release of the movie JFK. The director of the film, Oliver Stone, called for the remaining CIA and FBI documents pertaining to the assassination of Kennedy to be released. Clifford Krauss, reported in the New York Times that members of the Kennedy family supported this move. The historian, Stephen Ambrose, argued that “the crime of the century is too important to be allowed to remain unsolved and too complex to be left in the hands of Hollywood movie makers.” Louis Stokes, who had chaired the House Select Committee on Assassinations, also called for the files to be unclassified.
The President John F. Kennedy Assassination Records Collection Act of 1992, or the JFK Records Act, was passed by the United States Congress, and became effective on 26th October, 1992. The Act requires that each assassination record be publicly disclosed in full, and be available in the collection no later than the date that is 25 years after the date of enactment of the Act (October 26, 2017), unless the President of the United States certifies that: (1) continued postponement is made necessary by an identifiable harm to the military defense, intelligence operations, law enforcement, or conduct of foreign relations; and (2) the identifiable harm is of such gravity that it outweighs the public interest in disclosure.
Assassination Records Review Board included John R. Tunheim (United States District Court Judge; District of Minnesota), Dr. Henry F. Graff (Professor Emeritus of History at Columbia University), Dr. Kermit L. Hall (Professor of History and Law at The Ohio State University), Dr. William L. Joyce (Associate University Librarian for Rare Books and Special Collections at Princeton University) and Dr. Anna K. Nelson (Professor of History at The American University).
Witnesses who appeared before the Assassination Records Review Board included Peter Dale Scott, Jim Marrs, Gary Mack, Adele Edisen, Martin Shackelford, Michael Kurtz, David Lifton and Josiah Thompson.
There are currently over 50,000 pages of government documents relating to the assassination that have not been released.