There were nine official Pearl Harbor Investigations during the 1940s, plus at least one more in the 1990s, iirc.
In addition, dozens of authors have done their own Pearl Harbor investigations, attempting to tease out of existing data support for their favorite theories.
The results of all these investigations have not been 100% satisfactory to anyone -- those looking for data to support their conspiracy theories find no "smoking guns", while those wishing to prove President Roosevelt's inner circle "innocent" of all conspiracy charges have plenty that can't be 100% dismissed.
The relevant question here is: why weren't Kimmel and Short better warned?
The trip of Secretary of the Navy Knox to Hawaii, his candid report, his statement that “the United States services were not on the alert against the surprise air attack on Hawaii,” and the immediate appointment by the President of the five-man board of inquiry are all reassuring evidences of the government’s determination that the same factors that contributed to the Japanese success at Hawaii – surprise, over-confidence amounting to a complacent sense of security and a lack of military alertness – will not again operate against us.
(snip)
Second, the intelligence services of the Army and Navy and counter-espionage services of the government seem to have failed to collate and correctly evaluate the Japanese military strength; to obtain any warning of the impending Japanese attack, preparations for which must have been started weeks before Dec. 7, “a date that will live in infamy,” or to counter Japanese fifth columnist and espionage activities in Hawaii.
It looks to me like there were plenty of shortcomings. Just as with the terror attacks of 9/11, America was simply not vigilant enough, and we should have done better. The similarities between the TWO dates that will live in infamy are striking. The relevant question today is: Are we NOW vigilant enough?