Do you believe that Lee Harvey Oswald acted alone, or was involved at all in the assassination of John F. Kennedy or do you think JFK's death was...

I think Lee Harvey Oswald acted alone. First, the Warren Commission decided Oswald carried out the assassination alone and that there was no conspiracy. The 888-page report, concluded in 1964, demonstrated that the same bullets used to kill Kennedy came from the model of rifle Oswald used. Oswald was a trained military sharpshooter, so firing three shots in three seconds from a bolt-action rifle would not have been impossible. Oswald worked in the Texas Book Depository, so it would not have been suspicious for him to be there during the parade. Also, the Zapruder film, upon recent digital analysis, shows Oswald in the Depository at the window from where the shots were fired.  

While it is popular to believe the Soviets, Castro, or the CIA were parties to the assassination, there has not been any conclusive evidence to prove Kennedy was killed by any of these groups. The only bullets recovered from the crime scene were from Oswald's cheap mail-order rifle. Oswald had the expertise to fire the shots. Since there is no other convincing evidence, one has to go with the findings of the Warren Commission and declare Oswald the most likely shooter.