The Warren Report, in September, 1964.
Its 888-page final report was presented to President Johnson on September 24, 1964, and made public three days later. It concluded that Lee Harvey Oswald acted alone in the killing of Kennedy and the wounding of Texas Governor John Connally, and that Jack Ruby acted alone in the murder of Oswald. The Commission's findings have since proven controversial and been both challenged and supported by later studies.
Extensive investigation indicates that the killer acted alone and on his own accord. Many people think otherwise but none have come forward with any solid evidence to support their various theories of conspiracy,
The Commission concluded that Oswald acted alone. There has been plenty of rumour but no hard evidence. Oliver Stone tried to "Hollywood" the story but that's what movies do to history---they mangle it.
The Warren Commission finding was the he acted alone.
After an extensive investigation, the Warren commission concluded that Oswald acted alone in the shooting. There are many people who have other theories but no indisputable evidence.
Lee Harvey Oswald was a lone shooter on the sixth floor of the Texas School Book Depository. He fired 3 shots: the first missed the presidential limo, the second hit JFK in the throat and passed on to Governor Connallys chest, right wrist, and left thigh, and the third hit JFK somewhere between his right ear and eye and above which killed him.
Johnson was in his room at the Kirkwood Hotel in Washington when Lincoln was assassinated, but George Atzerodt, the conspirator who was supposed to assassinate the Vice President never acted.
Texas The Texas Book Depository on Deeley Plaza in Dallas Sixth floor, Texas School Book Depository on Dealey Plaza, Dallas, TX. This is the lone gunman version approved by the Warren Commission, which determined that Lee Harvey Oswald acted alone. Many believe there was a second gunman on the "grassy knoll" ahead and to the right of the president's limousine, but this has never been substantiated.
There is an endless harangue over whether Lee Harvey Oswald acted alone or whether there were other shooters and whether the Cubans or the Soviets or the Mafia were involved.
Your question has been extensively researched and debated. Best evidence is that he acted alone but many do not agree and all the facts will never be known.
James Earl Ray acted alone in the assassination of Martin Luther King Jr. There is no evidence to suggest that he was hired by anyone else to commit the crime.
That is was a single shooter, Lee Harvey Oswald, and that Texas Governor Connally was wounded by a Magic bullet. They also determined that Jack Ruby acted alone when he killed Oswald.