On the afternoon of 22nd November, 1963, Banister and Jack Martin went drinking together. On their return to Banister's office the two men got involved in a dispute about a missing file. Banister became so angry that he he drew his Magnum revolver and hit Martin with it several times. Martin was so badly injured that he had to be detained in the local Charity Hospital.
Over the next few days Martin told friends that Guy Banister and David Ferrie had been involved in the assassination of John F. Kennedy. According to Martin, Ferrie was the getaway man whose job it was to fly the assassin out of Texas. He also claimed that Ferrie knew Lee Harvey Oswald from their days in the New Orleans Civil Air Patrol and had given him lessons on how to use a rifle with a telescopic sight.
On 25th November, Martin was contacted by the Federal Bureau of Investigation. He told them that he thought Ferrie had hypnotized Oswald into assassinating Kennedy. The FBI considered Martin's evidence unreliable and decided not to investigate Banister and Ferrie.
This information eventually reached Jim Garrison, the district attorney of New Orleans. He interviewed Martin about these accusations. Martin claimed that during the summer of 1963 Banister and David Ferrie were involved in something very sinister with a group of Cuban exiles.
Jim Garrison now became convinced that a group of right-wing activists, including Guy Banister, David Ferrie, Carlos Bringuier and Clay Shaw, were involved in a conspiracy with the CIA to kill John F. Kennedy.
Roberts said she was in the office when Banister suggested that Lee Harvey Oswald should establish a local Fair Play for Cuba Committee. This story was supported by her daughter who met Oswald during this period.
According to Delphine Roberts, Lee Oswald walked into her office sometime in 1963 and asked to fill in the forms for accreditation as one of Banister's "agents." Mrs. Roberts told me, "Oswald introduced himself by name and said he was seeking an application form. I did not think that was really why he was there. During the course of the conversation I gained the impression that he and Guy Banister already knew each other. After Oswald filled out the application form Guy Banister called him into the office. The door was closed, and a lengthy conversation took place. Then the young man left. I presumed then, and now am certain, that the reason for Oswald being there was that he was required to act undercover."
Mrs. Roberts said she was sure that whatever the nature of Banister's "interest" in Oswald, it concerned anti-Castro schemes, plans which she feels certain had the support and encouragement of government intelligence agencies. As she put it, "Mr. Banister had been a special agent for the FBI and was still working for them. There were quite a number of connections which he kept with the FBI and the CIA, too. I know he and the FBI traded information due to his former association...."