Within 2 to 3 days, two top government officials express their common concern that the public must be convinced that Oswald is the real assassin of the president, and that there is no conspiracy.
Nicholas Katzenbach, the deputy attorney general at the time, wrote a memo the day after Hoover wrote his memo, restating similar concerns:
"The public must be satisfied that Oswald was the assassin; that he did not have confederates who are still at large; and that evidence was such that he would have been convicted at trial."
For any investigator to think he or she has all the evidence to rule out any accomplices in an assassination within 3 days, is ridiculous. It was an effort to frame Oswald - most likely motivated as a cover-up.