Lee harvey Oswald was the man accused of assasinating President John F Kennedy in Texas in 1963 - Oswald was himself shot dead by Jack Ruby before he came to trial. The facts of the case - that Oswald could not have fired quickly or accurately enough to have hit Kennedy from the book depository window - has given rise to several 'conspiracy' theories, which are debated to this day.
Just a small point - Oswald didn't shoot from the 'grassy knoll', he was hiding in the the Texas School Book Depository. A second, unknown gunman was hiding in the grassy knoll.
Or not, depending who you believe. How many bullets fired depends on whetehr you believe Governor John Conelly or the ballistics expert....If you believe there were more bullets then Oswald cant have fired them. If you believe there were less then he can.