Ben,
I think you're somewhat understating the HSCA's findings.
-- The HSCA said the fact that scientific evidence indicated two gunmen were probably involved "compels acceptance" and "demands a reexamination of all that was thought to be true in the past," adding that the committee's investigation "showed a variety of relationships" that may have developed into a murder plot, and that Oswald and Ruby were not the "loners" the WC had painted them to be:
The scientific evidence available to the committee indicated that it is probable that more than one person was involved in the President's murder. That fact compels acceptance. And it demands re-examination of all that was thought to be true in the past. Further, the committee's investigation of Oswald and Ruby showed a variety of relationships that may have matured into an assassination conspiracy. Neither Oswald nor Ruby turned out to be "loners," as they had been painted in the 1964 investigation. (HSCA Report, p. 180)
-- The HSCA said the acoustical evidence established a "high probability" that "two gunmen fired at President John F. Kennedy" (HSCA Final Report, p. 65).
-- The HSCA said the acoustical evidence showed there was a 95% probability that a shot was fired from the grassy knoll (HSCA Final Report, pp. 65-60; 5 HSCA 499-690).
The NRC/NAS panel that critiqued the HSCA's acoustical evidence could only reduce the probability of the grassy knoll shot from 95% to 77.7% by introducing two outright errors into their calculations. Even then, a probability of 77.7% is a high probability. When expressing a 77.7% probability in everyday language, statisticians use such terms as "highly likely" and "highly probable." Subsequent analysis of the acoustical evidence has found that the probability of the grassy knoll shot is virtually 100%.
-- The HSCA concluded that certain Mafia leaders had the "motive, opportunity, and means" to assassinate JFK, and said there was evidence that some Mafia leaders had expressed a desire to see JFK killed (HSCA Final Report, pp. 149-181).
-- The HSCA said Silvia Odio and her sister Annie were credible (HSCA Final Report, pp. 137-139), thus endorsing Silvia Odio's account that anti-Castro Cubans visited her and then called her and portrayed Oswald as an unstable ex-Marine who believed that JFK should have been assassinated after the Bay of Pigs and who said it would be "so easy" to kill Kennedy.
The HSCA also roundly criticized the WC's handling and rejection of Silvia Odio's account.
-- The HSCA said photographic evidence showed that boxes were being rearranged in the sixth-floor window within 2 minutes after the shooting (6 HSCA 109-115; 4 HSCA 422-423).
-- The HSCA said the first hit on JFK occurred at around Z190 (HSCA Final Report, p. 82; 2 HSCA 15). Of course, during this timeframe, the sixth-floor gunman's view of JFK would have been obstructed by the intervening oak tree.
-- The HSCA rejected the WC's tale that Ruby walked down the Main Street ramp to enter the police basement to shoot Oswald. The HSCA said that Ruby may have had inside help getting into the basement. The HSCA noted that shortly before Ruby entered the basement, someone ordered the removal of the security guards from the area of the garage closest to the stairway that Ruby used. The HSCA was “troubled by the apparently unlocked doors along the stairway route and the removal of security guards from the area of the garage nearest the stairway shortly before the shooting” (HSCA Report, p. 157).
-- The HSCA noted that the timing of Ruby’s entrance into the police basement
was so perfect that it made it difficult to accept mere coincidence, and it is unlikely that Ruby entered the basement without some sort of assistance. This might have been in the form of knowledge of the Oswald transfer plans, direct help in entering the basement, or direct help in entering and shooting Oswald. (9 HSCA 146)
-- The HSCA noted that Sergeant Patrick Dean was in charge of security in the basement, that Dean failed his polygraph test, that Dean had close ties to Dallas crime boss Joseph Civello, and that Civello and Ruby knew each other (9 HSCA 158-159).
-- The HSCA said Ruby lied about why he shot Oswald, that Ruby lied about not being at Parkland Hospital soon after the assassination, that Ruby had significant Mafia ties, and that Ruby's actions in the 24 hours leading up to the shooting of Oswald were suspicious (9 HSCA 125-180).
-- The HSCA FPP endorsed the SBT but they did so in a way that destroyed the SBT. They admitted that the back wound was at least 2.5 inches lower than where the WC placed it, that the back wound was below the throat wound, and that the bullet hit the back at an upward angle and then tunneled at an upward angle (1 HSCA 256; 7 HSCA 86-87, 175; 7 HSCA 100, Figure 12). To make this trajectory work, the FPP had to assume that JFK was leaning substantially forward when the bullet hit the back, an assumption that the HSCA's trajectory expert, NASA's Dr. Thomas Canning, ignored (compare 7 HSCA 100, Figure 12, with 2 HSCA 177, JFK Exhibit F-142).
-- The HSCA strongly criticized the WC's investigation and argued that the Commission failed to properly follow up on leads that pointed to conspiracy (HSCA Report, pp. 256-261).
-- The HSCA acknowledged that three witnesses gave statements to law enforcement agencies after the assassination that they saw two men in the sixth-floor window from which they believed the assassin had fired (12 HSCA 3-6).
-- The HSCA said that the puffs of smoke that several witnesses reported seeing on the grassy knoll could have come from gunfire from the knoll (12 HSCA 24-25).
-- The HSCA's final report criticized the performance of the Secret Service (SS) before and during the assassination (HSCA Final Report, pp. 227-236), noting the following failings, among others:
". . . the Secret Service did in fact possess information that was not properly analyzed and put to use with respect to a protective investigation in advance of President Kennedy's trip to Dallas."
". . . Secret Service agents in the Presidential motorcade in Dallas were not adequately prepared for an attack by a concealed sniper."
". . . the failure to arrange for prior inspection of buildings along the motorcade route" (a failure that even the WC acknowledged).
"No actions were taken by the agent in the right front seat of the Presidential limousine to cover the President with his body, although it would have been consistent with Secret Service procedure for him to have done so."
The last statement was overly gentle. Per SS regulation, it was SS agent Roy Kellerman's duty to immediately cover JFK with his body the moment he heard gunfire. In LBJ's vehicle, SS agent Rufus Youngblood took immediate action after hearing gunfire; he vaulted over the seat, shouted at those in the back seat to “get down,” and covered LBJ's body with his own. This is what Kellerman had a duty to do, but did not.
-- The HSCA staff report on the SS's performance, written by HSCA staff attorney Belford Lawson, went much further than the committee's final report. Lawson openly voiced suspicion that elements of the SS were part of the assassination conspiracy (Memorandum from HSCA staff attorney Belford Lawson to fellow HSCA members Gary Cornwell & Ken Klein, 8/15/77).
-- Before chief counsel G. Robert Blakey agreed to the CIA's edits of the HSCA Report's section on the Clinton witnesses, the section was more strongly worded. The CIA insisted on the insertion of the following qualifying statement:
While there were points that could be raised to call into question their credibility, it was the judgment of the committee that they were telling the truth as they knew it. (HSCA Report, p. 142)
This was not in the "Summary Memorandum" on the Clinton witnesses on which this section of the final report was based. The "Summary Memorandum" said that "Oswald must have been present at least two days in the Clinton-Jackson area" and that there was "clear indication" that Clay Shaw and David Ferrie were with him.
However, even the bottom-line statement in the final report said the committee was "inclined to believe" that Oswald was indeed in Clinton "in the company of David Ferrie, if not Clay Shaw":
As noted, the committee believed the Clinton witnesses to be telling the truth as they knew it. It was, therefore, inclined to believe that Oswald was in Clinton, La., in late August, early September 1963, and that he was in the company of David Ferrie, if not Clay Shaw. The committee was puzzled by Oswald's apparent association with Ferrie, a person whose anti-Castro sentiments were so distant from those of Oswald, the Fair Play for Cuba Committee campaigner. But the relationship with Ferrie may have been significant for more than its anti-Castro aspect, in light of Ferrie's connection with G. Wray Gill and Carlos Marcello. (HSCA Final Report, p. 145)
I could cite other HSCA examples, but this reply is already long enough.