Here is an excerpt from the 1979 House Select Committee report on JFK assassination which (I believe) is sort of the last official view. Interesting findngs.
I. Findings of the Select Committee on Assassinations in the Assassination of President John F. Kennedy in Dallas, Tex., November 22, 1963
Lee Harvey Oswald fired three shots at President John F. Kennedy. The second and third shots he fired struck the President. The third shot he fired killed the President.
President Kennedy was struck by two rifle shots fired from behind him. The shots that struck President Kennedy from behind him were fired from the sixth floor window of the southeast corner of the Texas School Book Depository building.
Lee Harvey Oswald owned the rifle that was used to fire the shots from the sixth floor window of the southeast comer of the Texas School Book Depository building. Lee Harvey Oswald, shortly before the assassination, had access to and was present on the sixth floor of the Texas School Book Depository building. Lee Harvey Oswald’s other actions tend to support the conclusion that he assassinated President Kennedy.
Scientific acoustical evidence establishes a high probability that two gunmen fired at President John F. Kennedy. Other scientific evidence does not preclude the possibility of two gunmen firing at the President. Scientific evidence negates some specific conspiracy allegations.
The committee believes, 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 committee believes, on the basis of the evidence available to it, that the Soviet Government was not involved in the assassination of President Kennedy.
The committee believes, on the basis of the evidence available to it, that the Cuban Government was not involved in the assassination of President Kennedy.
The committee believes, on the basis of the evidence available to it, that anti-Castro Cuban groups, as groups, were not involved in the assassination of President Kennedy, but that the available evidence does not preclude the possibility that individual members may have been involved.
The committee believes, on the basis of the evidence available to it, that the national syndicate of organized crime, as a group, was not involved in the assassination of President Kennedy, but that the available evidence does not preclude the possibility that individual members may have been involved.
The Secret Service, Federal Bureau of Investigation and Central Intelligence Agency were not involved in the assassination of President Kennedy.
http://www.archives.gov/research/jfk/select-committee-report/summary.html#kennedy
Which can be boiled down to this:
Oswald did it. The Warren Commission was right about the basic facts. But according to the acoustic evidence someone unknown person for unknown reasons fired an unknown shot from the grassy knoll that didn't hit anything.
Of course later on the acoustic evidence was debunked, which left only the Oswald did it part still intact.