I have difficulty believing in conspiracies involving large numbers of people. Someone will leak information to the press, get drunk and brag to his girlfriend or wife, or have a death bed confession.
I think Lee Harvey Oswald acted alone. However, I can think of two conspiracies involving a small number of people.
First, we know that when John Kennedy was president the CIA was involved in efforts to assassinate Fidel Castro. Several KGB agents assigned to protect Castro may have decided to hit back at Kennedy. This would not have been an action by "the KGB" but an action by several rogue KGB agents acting on their own.
Lee Harvey Oswald was a Communist sympathizer who belonged to the Fair Play for Cuba Committee. The rouge KGB agents may have contacted Oswald when he was in Russia and talked him into going back to get Kennedy.
If the Warren Commission uncovered this they would have covered it up to avoid the possibility of war with Russia. It just can't go before the American people and say "Our president was killed by the Russians."
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The Los Angeles Times, NOV. 9, 1997
WASHINGTON —
The money, muscle and influence of organized crime helped John F. Kennedy win the closely contested 1960 election, investigative journalist Seymour M. Hersh contends in a new book on the Kennedy presidency.
And once Kennedy was inaugurated, Robert F. Kennedy, his brother and attorney general, refused to pursue FBI evidence into widespread voting fraud, Hersh alleges.
In “The Dark Side of Camelot,” Hersh claims that the Mafia was brought into the Kennedy presidential campaign--and helped the Democrat carry the key state of Illinois--mainly at the instigation of Joseph P. Kennedy Sr., founder of the family political dynasty.
Politics: Seymour M. Hersh tome attacks Kennedy's Camelot legacy
www.latimes.com
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I have heard this story before from other sources. Let's assume it is true. After Kennedy was inaugurated as president Bobby Kennedy as Attorney General began to go after the Mafia.
Those who have studied the Mafia have said that Mafia gangsters will not attack someone who goes after them if that person has a clean record with them. If that person has accepted favors from them they will feel betrayed, and they will try to kill the person going after them.
Mafia gangsters may have contacted Oswald and persuaded him to shoot Kennedy. Again this would not have been a conspiracy by "The Mafia" but by several Mafia gangsters acting together on their own.
Jack Ruby, who killed Oswald, is believed to have had underworld connections. He may have decided to silence Oswald, knowing that Oswald was unbalanced and unreliable.
If the Warren Commission had uncovered this conspiracy it may not have wanted to reveal that the presidential election of 1960 was fraudulent.
Despite all this, I think Oswald acted on his own for reasons of his own, and which can only be understood psychologically.
Those who attribute a world changing catastrophe to a conspiracy blame a group that they dislike for other reasons. Those who blame the assassination of President Kennedy are usually on the left. They blame left wing hate targets such as the CIA, the FBI, the Pentagon, the defense industry, and so on.