In 1979, the U.S. House Select Committee on Assassinations concluded that President Kennedy was "probably assassinated as a result of a conspiracy." This was not a fringe claim. It was the official finding of a two-year Congressional investigation with subpoena power, 25 staff attorneys, and access to classified records. The Sixth Floor Museum treats it as a footnote.
The Warren Commission issued its report in September 1964, concluding that Lee Harvey Oswald acted alone. Within a decade, public confidence in that conclusion had collapsed. By the mid-1970s, polls showed that a majority of Americans did not believe the official account. In 1976, the U.S. House of Representatives created the Select Committee on Assassinations to reinvestigate the murders of President Kennedy and Dr. Martin Luther King Jr.
The HSCA operated for two years with full Congressional authority: subpoena power, access to classified materials, forensic experts, ballistic analysts, and photographic evidence specialists. It was the most comprehensive federal investigation of the Kennedy assassination ever conducted — more thorough than the Warren Commission, which had no independent investigative staff and relied almost entirely on the FBI's fieldwork.
On March 29, 1979, the committee issued its final report. The central conclusion overturned the Warren Commission: Kennedy was "probably assassinated as a result of a conspiracy." The committee also found that the Warren Commission, the FBI, the CIA, and the Secret Service had all been deficient in their original investigations. It recommended the Justice Department investigate further. The Justice Department never did.
The HSCA's conspiracy finding rested significantly on acoustic evidence analyzed by Bolt Beranek and Newman Inc. (BBN), one of the foremost acoustics firms in the world, and independently verified by Queens College professor Mark Weiss and his research associate Ernest Aschkenasy.
A Dallas Police Department dictabelt recording — captured by a motorcycle officer's open microphone in Dealey Plaza — contained impulse patterns consistent with gunfire. BBN identified four shots, not three. The fourth impulse pattern matched the acoustic signature of a shot fired from the grassy knoll, ahead and to the right of the presidential motorcade — a location inconsistent with shots from the Texas School Book Depository behind the motorcade.
"The committee believes, on the basis of the evidence available to it, that two gunmen fired at President John F. Kennedy. [...] The committee believes, on the basis of the evidence available to it, that the fourth shot came from the grassy knoll."
— HSCA Final Report, Volume I, Findings, Section I.B., p. 65The acoustic evidence was the HSCA's most dramatic finding, but it was not the committee's only basis for the conspiracy conclusion. The committee also identified significant failures by the CIA, FBI, and Secret Service to share critical information with the Warren Commission — failures the 2025 declassifications have now confirmed and extended.
The acoustic evidence and its significance are not featured in the museum's permanent exhibits. The HSCA's finding of "two gunmen" is not presented as a Congressional conclusion based on scientific analysis. When the HSCA is mentioned, the 1982 NAS critique is given equal or greater weight — without noting that subsequent peer-reviewed research has supported the original findings.
The HSCA reexamined witness testimony that the Warren Commission had collected but effectively discounted. The pattern was striking: a substantial number of witnesses in Dealey Plaza reported hearing shots from the direction of the grassy knoll — the same location identified by the acoustic analysis.
"The Warren Commission failed to investigate adequately the possibility of a conspiracy to assassinate the President."
— HSCA Final Report, Volume I, Section I.C., p. 95The HSCA did not rely on witness testimony alone. But the convergence of acoustic evidence, witness accounts, and the physical evidence of the President's movement at the moment of the fatal shot formed a body of evidence that the committee found sufficient to overturn the Warren Commission's lone-gunman conclusion.
The museum's narrative does not present the full scope of witness testimony pointing to the grassy knoll. Witnesses who heard or saw evidence of shots from the front are not given prominence. The convergence of witness testimony, acoustic evidence, and physical evidence is not presented as the HSCA presented it — as a mutually reinforcing body of evidence supporting conspiracy.
Beyond the physical and acoustic evidence, the HSCA documented systematic failures by federal agencies to provide the Warren Commission with critical information about Lee Harvey Oswald and the circumstances of the assassination. These findings, initially limited by the CIA's refusal to fully cooperate, have been dramatically vindicated by the 2025 declassifications.
The HSCA's findings on institutional failure were carefully worded in 1979 — the committee did not have access to the full record. The 2025 declassifications have confirmed that what the HSCA identified as "deficiency" was, in key instances, active concealment. Three senior CIA officials have now been documented lying under oath about their knowledge of Oswald prior to the assassination. The committee was right to suspect worse than it could prove.
The museum does not present the HSCA's findings of institutional failure with the weight they deserve. The CIA's obstruction of both the Warren Commission and the HSCA is not featured. The FBI's destruction of the Hosty note is not highlighted. The Secret Service failures are not emphasized. The narrative treats these agencies as cooperative participants in a thorough investigation, rather than as entities whose conduct the HSCA formally criticized.
The Sixth Floor Museum presents the Warren Commission's conclusions as the primary narrative. Here is how the two investigations actually compare.
| Category | Warren Commission (1964) | HSCA (1979) |
|---|---|---|
| Central conclusion | Oswald acted alone. No credible evidence of conspiracy. | Kennedy was "probably assassinated as a result of a conspiracy." Two gunmen fired at the President. |
| Number of shooters | One (Oswald) | Two. Second gunman fired from the grassy knoll. |
| Investigation staff | No independent investigative staff. Relied on FBI fieldwork. | 25+ staff attorneys, forensic experts, ballistics specialists, photographic analysts. |
| Duration | 10 months (November 1963 – September 1964) | 2 years (1977 – 1979) |
| Scientific evidence | Neutron activation analysis on bullet fragments (later discredited). | Acoustic analysis, enhanced photographic analysis, forensic pathology panel, ballistic trajectory reconstruction. |
| Witness testimony | Collected but marginalized accounts pointing to grassy knoll. | Systematically analyzed. Documented 51+ witnesses indicating shots from the knoll area. |
| CIA cooperation | Commission accepted CIA representations at face value. | Found CIA was "deficient in the collection and sharing of information" with the Warren Commission. The CIA actively obstructed the HSCA itself via the Joannides liaison. |
| Recommendation | Case closed. | Referred to the Department of Justice for further investigation. The DOJ never acted. |
The HSCA's "probable conspiracy" finding is not a minority opinion from the fringes of American politics. It is the most recent official conclusion of a duly authorized Congressional investigation with full access to the evidentiary record available at the time. No subsequent federal investigation has overturned it. No court of law has challenged it. No act of Congress has rescinded it.
The Warren Commission concluded Oswald acted alone. Fifteen years later, Congress concluded he probably did not. Both of these are official findings of the United States government. A museum dedicated to the assassination has an obligation to present both — and to give the more recent, more thorough investigation appropriate weight.
The Sixth Floor Museum does not do this. The Warren Commission's narrative forms the backbone of the museum's permanent exhibits. The HSCA is acknowledged, but its central conclusion — the one that overturns the Warren Commission — is presented as one of many "theories" rather than what it is: a Congressional finding based on scientific evidence, witness testimony, and the most comprehensive investigation the federal government has conducted into the assassination.
This is not a matter of opinion. It is a matter of public record. Over 300,000 people visit the Sixth Floor Museum each year. Many leave believing the question of conspiracy is settled — that Oswald acted alone and the case is closed. They are not told that their own Congress concluded otherwise, based on evidence the Warren Commission never examined.
DealeyTruth exists to ensure the full record is available. Not the Warren Commission's version. Not the museum's version. The complete record — including the parts that are inconvenient for institutions that have built their narrative around a conclusion that Congress itself rejected.
Every finding described above is drawn from official government records, Congressional reports, and peer-reviewed research. Nothing here requires you to take our word for it.
The HSCA concluded conspiracy. The 2025 declassifications confirmed CIA deception. The Sixth Floor Museum has addressed neither. Help us build the institution that presents the complete record.