What is the theme in Case Closed: Lee Harvey Oswald and the Assassination of JFK by Gerald L. Posner?

Conspiracy or the attempt to provide conspiracy is another theme of the book. Conspiracy can be defined as the concerted action of two or more people to commit a criminal act. Many people had problems accepting Oswald as the lone assassin. The same with Ruby. A week after the assassination, a poll indicated that less than one-third of the population believed that Oswald acted alone. They believed that he was a part of something much bigger involving the Russians, Cubans, Mafia, or CIA.