Gary Underhill was born in Brooklyn on 7th August, 1915. He graduated from Harvard in 1937 and during the Second World War he served with the Military Intelligence Service (6 July 1943 to May 1946). After leaving the Office of Strategic Services (OSS) he worked on specific projects for the Central Intelligence Agency. He was also military affairs editor for Life Magazine.
After the assassination of President John F. Kennedy, Underhill told his friend, Charlene Fitsimmons, that he was convinced that he had been killed by members of the CIA. He also said: "Oswald is a patsy. They set him up. It's too much. The bastards have done something outrageous. They've killed the President! I've been listening and hearing things. I couldn't believe they'd get away with it, but they did!"
Underhill believed there was a connection between Executive Action, Fidel Castro and the death of Kennedy: "They tried it in Cuba and they couldn't get away with it. Right after the Bay of Pigs. But Kennedy wouldn't let them do it. And now he'd gotten wind of this and he was really going to blow the whistle on them. And they killed him!"
Underhill told friends that he feared for his life: "I know who they are. That's the problem. They know I know. That's why I'm here. I can't stay in New York."
Gary Underhill was found dead on 8th May 1964. He had been shot in the head and it was officially ruled that he had committed suicide. However, in his book, Destiny Betrayed, James DiEugenio claimed that the bullet entered the right-handed Underhill's head behind the left ear.
From Malcolm Blunt