The Warren Commission was only the first of several federal investigations which looked into the Kennedy assassination:
Warren Commission – Appointed by President Johnson, the Warren Commission found that Lee Harvey Oswald acted alone.
Garrison Investigation – New Orleans DA Jim Garrison’s investigation ended in the acquittal of Clay Shaw.
Rockefeller Commission – Vice-President Nelson Rockefeller's post-Watergate probe conducted a limited analysis of JFK photographic and medical evidence.
Church Committee – This wide-ranging Senate Committee investigation documented widespread abuses by FBI and CIA, including CIA plots to assassinate Fidel Castro.
House Select Committee on Assassinations – Congress created the House Select Committee on Assassinations, which re-investigated the JFK case and found the Kennedy was "probably assassinated as a result of a conspiracy."
Assassination Records Review Board – The Assassination Records Review Board oversaw massive declassifications in the 1990s and conducted its own interviews.
Warren Report - Report of the President's Commission on the Assassination of President Kennedy, 1964.
Clay Shaw Trial Transcript - Transcript of the trial of Clay Shaw, culmination of the Garrison investigation, 1969.
Rockefeller Report: Chapter 19 - Allegations Concerning the Assassination of President Kennedy, 1975.
Church Committee: Book V - The Investigation of the Assassination of President John F. Kennedy: Performance of the Intelligence Agencies, 1976.
HSCA Final Assassinations Report - Report of the House Select Committee on Assassinations, 1979.
ARRB Final Report - Final Report of the Assassination Records Review Board, 1998.