The last government body to conduct an official investigation into the JFK assassination was the House Select Committee on Assassinations (HSCA), which investigated the case from 1977 to 1979. The HSCA’s investigation was a major step forward in the case. HSCA investigators and experts found a large amount of new evidence and laid the foundation for the development of important additional evidence by later researchers.
Lone-gunman theorists cite some of the HSCA’s research, but they reject most of the committee’s main conclusions, especially the finding that there was probably a conspiracy and that four shots were fired at JFK. Conspiracy theorists agree with most of the HSCA’s main conclusions, but many of them believe the committee avoided the facts on several key issues and too often failed to pursue important leads.
By any standard, the HSCA’s findings and research support the conspiracy view far more than they do the lone-gunman view. Here are some of the conclusions and evidences found in the HSCA’s report and in the HSCA’s hearings and exhibits:
* Kennedy was probably killed by a conspiracy. This was the key finding of the committee, a finding that the committee argued was supported by existing evidence and by additional evidence that it developed during its investigation.
* Four shots were fired during the assassination, one of them from the grassy knoll. Oswald fired the three other shots.
* Two gunmen were involved in the assassination, one of whom fired from the grassy knoll.
* Jack Ruby had significant Mafia ties.
* Ruby lied about his reason for shooting Oswald.
* Ruby's shooting of Oswald resembled a Mafia hit to silence a witness or conspirator.
* The WC ignored the clear weight of the evidence regarding how Ruby entered the DPD basement to shoot Oswald.
* Someone helped Ruby get into the DPD basement.
* The DPD left doors unlocked along Ruby's route into the basement.
* The DPD removed security from the area near the stairway that Ruby used to enter the basement shortly before he entered the basement via that stairway.
* Oswald might have had links to Jack Ruby.
* Ruby's AGVA alibi doesn't seem to be a credible explanation for all the long-distance phone calls Ruby made to Mafia contacts all across the country after Kennedy's visit to Dallas was announced.
* Ruby's polygraph test indicates he was quite possibly lying when he denied he was involved in the assassination.
* Photographic evidence shows that someone was moving boxes in the sixth-floor window within 2 minutes after the shooting (obviously, it could not have been Oswald).
* Silvia Odio's account of meeting with Oswald in company with two anti-Castro Cubans at a time when Oswald was supposedly in Mexico City is credible.
* A Dallas police dictabelt recording contains four impulses that are the result of the sounds of four gunshots that were fired in Dealey Plaza during the shooting (and possibly as many as seven to nine such impulses). One of these impulses was caused by a shot that came from the grassy knoll.
* Connally was hit by the same bullet that hit Kennedy, but the Zapruder film shows Kennedy was first hit at around Z188-190. (Lone-gunman theorists now reject this conclusion about when Kennedy was first hit because they know it proves there were four shots and because they're now committed to the alleged magic-bullet hit occurring at Z224.)
* The eyewitness reports of seeing puffs of smoke above the firing point on the grassy knoll are credible.
* Abraham Zapruder's report that one of the shots caused a great reverberation around him indicates that shot came from the grassy knoll, since it is very unlikely that a shot from the sixth-floor window could have caused such a reverberation.
* The FBI and the CIA misled and withheld information from the WC.
* Military intelligence destroyed important evidence relating to the case that should not have been destroyed.
* The FBI failed to properly investigate an informant report that an anti-Castro activist named Homer S. Echevarria appeared to have advance knowledge of a plot to kill Kennedy. Just one day before the assassination, during a discussion about a shipment of illegal weapons for anti-Castro activities, Echevarria told the informant that his anti-Castro group had plenty of money and that they would proceed "as soon as we take care of Kennedy." The Secret Service tried to investigate the matter, but the FBI made it clear it wanted the investigation halted, and, incredibly, the FBI itself did not pursue the issue further. The HSCA noted that Echevarria was associated with Juan Francisco Blanco-Fernandez, military director of the anti-Castro group DRE, and that the arms deal was being financed through one Paulino Sierra Martinez by hoodlum elements in Chicago and elsewhere. The committee also found that Echevarria may have been a member of the 30th of November anti-Castro organization, adding,
The 30th of November group was backed financially by the Junta del Gobierno de Cuba en el Exilio (JGCE), a Chicago-based organization run by Paulino Sierra Martinez. JGCE was a coalition of many of the more active anti-Castro groups that had been rounded in April 1963; it was dissolved soon after the assassination. Its purpose was to back the activities of the more militant groups, including Alpha 66 and the Student Directorate, or DRE, both of which had reportedly been in contact with Lee Harvey Oswald. Much of JGCE's financial support, moreover, allegedly came from individuals connected to organized crime. (HSCA Report, p. 134)
* Security arrangements for the presidential motorcade might have been uniquely insecure.
* Although the committee said it "could not credit" former anti-Castro leader Antonio Veciana's story of having seen a CIA officer meet with Oswald before the assassination, the committee did find some support for aspects of Veciana's story. Veciana claimed that prior to the assassination the CIA assigned him a case officer who went by the name of Maurice Bishop. Veciana said he saw Oswald and Bishop talking on one occasion. Some of the committee's staff suspected that Bishop's real name was David Atlee Phillips, a CIA officer who had been heavily involved in anti-Castro activities.
* The committee concluded Veciana probably did in fact have a case officer from some government agency, and it noted the CIA had assigned case officers to lesser figures in the anti-Castro movement. The committee found a record of $500 in operational expenses, given to Veciana by a person with whom the CIA had maintained a longstanding operational relationship.
* Phillips denied under oath that he had even known Veciana. The committee said it suspected Phillips was lying when he denied knowing Veciana, given the fact that Veciana was a prominent figure in the anti-Castro Cuban exile community, and that Phillips was deeply involved in anti-Castro activities.
* Veciana declined to identify Phillips as Bishop, although Veciana also said Phillips bore a physical resemblance to Bishop. Veciana also told a committee staffer that he wouldn't disclose that Phillips was Bishop even if he were. Based on the way Veciana acted when he said this, the staffer came away suspecting Veciana may have been trying to tell him Phillips was Bishop after all.
* The committee's report includes a footnote that says the committee suspected Veciana was falsely denying that Phillips was Bishop! In other words, the committee in effect said that it suspected Phillips may have been Bishop and that Veciana knew he was but would not say so!
* A former CIA case officer who was assigned from September 1960 to November 1962 to the JM/WAVE station in Miami told the HSCA that Phillips had in fact used the alias Maurice Bishop.
* A former CIA director and a former CIA agent told the HSCA that a man named Maurice Bishop had worked for the CIA.
* The Clinton-Jackson witnesses who reported seeing Oswald with David Ferrie and Clay Shaw were credible.
* Mafia boss Carlos Marcello was a plausible suspect for having been involved in the assassination conspiracy.
* Oswald associated with David Ferrie, an ultra-right-winger who was involved in the Carlos Marcello Mafia organization. (Very strange company for an alleged Marxist to be keeping.)
* Oswald had ties to the Marcello crime organization.
* The Mafia had the means, motive, and opportunity to assassinate President Kennedy.
* In some Mafia hits, the Mafia hired a gunman through third parties to conceal their involvement and then had a Mafia man kill the gunman.
* Some anti-Castro Cubans may have been involved in the assassination conspiracy.
* Kennedy's autopsy was flawed and incomplete, and the autopsy doctors were not qualified or experienced enough to conduct a medical-legal autopsy involving gunshot wounds.
* There was a huge discrepancy between the autopsy doctors’ descriptions of the wounds and the wounds that the HSCA’s medical experts identified in the autopsy photos and x-rays. For example, according to the committee’s medical experts, the rear head entry wound was nearly 4 inches higher than where the autopsy doctors said it was in the autopsy report, even though the autopsy doctors had two good reference points from which to locate the wound (the hairline and the external occipital protuberance).
* The bullet that struck Kennedy in his back and allegedly exited his neck had a slightly upward trajectory. The HSCA medical experts even noted that the photos of the back wound showed the tissue inside the wound to be tunneled upward. (The committee's trajectory study ignored the pathology panel's placement of the back wound.)
* When the HSCA asked the autopsy doctors to explain why the autopsy report does not mention the 6.5 mm fragment that the committee’s medical experts identified in the autopsy skull x-rays, the doctors insisted that on the night of the autopsy they did not see the 6.5 mm fragment in the skull x-rays that they took. (Several medical doctors with training in radiology have examined the 6.5 mm fragment and determined that it is a fake image. The HSCA’s Larry Sturdivan has stated that the fragment must be an “artifact” on the x-rays, i.e., that it was not on the skull when the autopsy x-rays were taken.)
* The eyewitness reports of hearing shots from the grassy knoll are credible and cannot be dismissed as merely being the result of echoes.
* The HSCA was contacted by a former Dallas police officer who reported that right after the shots were fired, he saw a man who seemed to be "running away" in Dealey Plaza. He said the man ran to a car, threw something in the back of the car, and then took off at high speed. Tilson found this suspicious, followed the man’s car, and read the license plate number to his daughter, who was in the car with him:
In an interview in Dallas with HSCA investigators on August 26, 1978, Tom Tilson reported that he saw a man running from the plaza immediately after the shots. Tilson stated that on November 22, 1963, he was off duty from his job as a Dallas Police Department patrolman. At the time of the motorcade, he was driving east from Commerce Street and was approaching the triple underpass. He had already heard the report on his police radio that there had been a shooting at the motorcade and had seen the Presidential limousine travel at high speed from the underpass. As he was in the area of the triple underpass, Tilson saw a man "slipping and sliding" down the embankment on the north side of Elm Street west of the underpass. Tilson said the man appeared conspicuous because he was the only one running away from the plaza immediately after the shots. Tilson said that because of his speed, the man rammed against the side of a "dark" car which was parked there. Tilson said he then saw the man do something at the rear door portion of the car, like "throw something inside, then jump behind the wheel and take off very fast."
Tilson told the investigators that his 17 years of experiences as a policeman, combined with the radio broadcast of the shooting and this conspicuous man, caused him to "give chase" to the man speeding away from the direction of the plaza. He then saw the same "dark car" going south on Industrial Boulevard, and he followed it. As the car approached a toll road toward Ft. Worth, Tilson was within 100 feet and called out the license number, make, and model to his daughter, Dinah, who was riding with him. She wrote it down on a slip of paper. (12 HSCA 10-16)
* The WC failed to adequately investigate the possibility of conspiracy.
Here are links to the HSCA's report and to the HSCA hearings and exhibits:
https://www.archives.gov/research/jfk/select-committee-reporthttps://history-matters.com/archive/jfk/hsca/reportvols/contents.htm 
