What is the theme in Libra by Don DeLillo?

Placing blame is the main theme of the book. The novel begins with three CIA agents blaming President John Kennedy and Fidel Castro for the bad things that have happened in their careers and their lives. Win Everett and T-Jay Mackey blame Kennedy and Castro for the downfall of their careers. Larry Parmenter blames the failed invasion of the Bay of Pigs on his loss of reputation and business profits. This blame leads these three men to conspire together to take an unsuccessful shot at President Kennedy and eventually to assassinating the president.