Who believes Earl Warren or Hoover or followup investigations could be controlled by Katzenbach? And the news media? Katzenbach controlled them too?
If only it were just Katzenbach.
"The thing I am concerned about, and so is Mr. Katzenbach, is having something issued so we can convince the public that Oswald is the real assassin." - J. Edgar Hoover, 11/24/1963
Consequently, the WC started with a predetermined conclusion. The outline that Rankin presented in a January 11, 1964 memo had a section titled "Lee Harvey Oswald as the assassin of President Kennedy". This was before they took a single bit of testimony.