Another thing that Blakey's pro-conspiracy critics overlook is that Blakey could only go as far as the committee would let him go. The committee members were the ones who had the final say on the conduct of the investigation, on the wording of the final report, and on which documents were sealed and which were not.
For example, the Final Draft Report, which Blakey approved, then underwent revision, including by the CIA. The final published version watered down many valid statements in the Final Draft Report. For instance, the Final Draft Report said the following about the evidence of Mafia involvement:
There is solid evidence that Hoffa, Marcello, and Trafficante — three of the most important targets for criminal prosecution by the Kennedy administration — had discussions with their subordinates about murdering President Kennedy. Associates of Hoffa, Trafficante, and Marcello were in direct contact with Jack Ruby, the Dallas nightclub owner who killed the "lone assassin" of the president. (Final Draft Report, HSCA, p. 274)
This was a perfectly valid, factual statement, as many scholars have proved (e.g., Dr. Richard Mahoney, Dr. David Kaiser, Dr. David Scheim, and Lamar Waldron). But, this blunt statement did not make it into the published report.
Because the committee members could not stomach a fifth shot and a third gunman, Blakey insisted that the apparent gunshot impulse pattern at 140.3 on the dictabelt be ruled a false alarm, even though it passed the echo-delay matching test, and even though 8 of its 10 impulses matched the impulses of one of the Dealey Plaza test shots.
The problem was that this impulse pattern occurs 1.05 seconds after the 139.27 impulse pattern, and the alleged murder weapon simply could not have been fired that quickly. Thus, this shot would have had to be fired by another gunman shooting from behind (possibly from the nearby Dal-Tex Building or from another window on the sixth floor, keeping in mind that several witnesses reported seeing two men on the sixth floor shortly before the shooting).