JFK Assassination: Second Shooter from the Grassy Knoll

Introduction

The assassination of President John F. Kennedy on 22 November 1963 in Dallas, Texas has generated more conspiracy literature than almost any other event in modern American history. Within that broader landscape, the "second shooter from the grassy knoll" is the most persistently cited specific claim — the hypothesis that a gunman fired from behind a wooden stockade fence atop a grassy rise north of Elm Street in Dealey Plaza, adding a frontal shot to Lee Harvey Oswald's shots from the rear.

This page focuses on the grassy knoll claim specifically, not the broader JFK assassination conspiracy question. The claim has a particular evidentiary history centred on acoustic analysis, witness testimony, and film analysis. That evidence is examined below.

The Physical Setting

Dealey Plaza lies at the western edge of downtown Dallas. The Texas School Book Depository (TSBD), from which Oswald fired, stood at the northwest corner of the plaza. The presidential motorcade turned from Houston Street onto Elm Street and passed below the TSBD. The "grassy knoll" refers to a grassy embankment on the north side of Elm Street, leading up to a low wooden stockade fence near a railroad overpass. A person standing behind that fence would have had a clear line of sight to the motorcade as it passed below.

Witness testimony placed some attention on that area immediately after the shooting. Dallas Police officers ran toward the knoll within seconds. No gunman was found; no physical evidence of a shot from that location was recovered.

The Acoustic Evidence: Dictabelt and the HSCA

The most consequential evidentiary development came with the House Select Committee on Assassinations (HSCA), which reinvestigated the Kennedy assassination from 1976 to 1979.

The HSCA commissioned acoustic experts James Barger (BBN) and Mark Weiss and Ernest Aschkenasy to analyse a Dictabelt recording made by a Dallas Police motorcycle radio that was apparently left in the open-transmit position during the assassination. The analysis identified four impulse patterns that the experts interpreted as gunshots. Crucially, they identified one of these impulses as originating from the grassy knoll direction with a statistical confidence they characterised as 95%.

Based primarily on this acoustic analysis, the HSCA concluded in its 1979 final report that "scientific acoustical evidence establishes, beyond a reasonable doubt, that two gunmen fired at President John F. Kennedy." The HSCA found "probable conspiracy" and recommended a further investigation by the Department of Justice.

The NRC Rebuttal (1982)

The National Research Council (NRC) convened a panel specifically to review the acoustic evidence. The panel, chaired by Norman Ramsey, found that the Dictabelt impulse patterns the HSCA experts identified as gunshots were recorded approximately one minute after the assassination — not during it — and therefore could not be gunshots. The panel concluded that the acoustic evidence did not support the HSCA's findings. This remains the most authoritative scientific assessment of the acoustic evidence.

The FBI Analysis

The FBI also re-examined the acoustic evidence and reached conclusions consistent with the NRC, rejecting the identification of the alleged knoll impulse as a gunshot.

Witness Testimony

Witness accounts from Dealey Plaza are the other main pillar of the grassy knoll claim.

Some witnesses did report believing that shots came from the knoll area. Dallas Police officers ran toward the knoll immediately after the shots. A few witnesses reported smelling gunpowder near the knoll. Jean Hill, one of the closest witnesses on the south side of Elm Street, initially reported hearing shots from the knoll.

However:

• Witness accounts of the direction of gunfire are notoriously unreliable in open urban spaces, where sound reflects and echoes in unpredictable ways.
• Dallas law enforcement officers who immediately searched the area — including the area behind the fence — found no gunman, no spent casings, no physical disruption consistent with a recent firing position.
• Subsequent interviews and accounts by many of the same witnesses have been inconsistent; some later recalled impressions differently.
• The Warren Commission took extensive witness testimony and found it insufficient to establish a second shooter.

The witness evidence is genuinely mixed; it does not rise to the level of establishing the presence of a second shooter.

The Zapruder Film

Abraham Zapruder filmed the motorcade from an elevated position on the north side of Elm Street, producing the most complete visual record of the assassination. The film has been subjected to exhaustive analysis by independent photogrammetrists, forensic pathologists, and film specialists.

Conspiracy proponents have argued that the "back and to the left" movement of Kennedy's head in frame 313 (the headshot) indicates a shot from the front (the knoll) rather than the rear (the TSBD). The forensic response — accepted by most ballistics and pathology specialists — is that the movement pattern is consistent with a neurological and muscular response to a shot from behind: the jet effect and neuromuscular spasm can produce forward-then-backward movement after a rear shot. Additionally, earlier frames show Kennedy's body already moving forward before the backward motion.

No independent photogrammetric analysis has established a visual origin of the headshot from the knoll.

Physical Evidence: What Was Not Found

A second shooter at the grassy knoll would be expected to leave physical evidence. No such evidence has been produced:

• No second bullet or bullet fragments have been identified as originating from the knoll.
• No spent shell casings were found behind the fence or in the knoll area.
• Blood-spatter and wound trajectory evidence from the autopsy is consistent with a rear entry wound. The Warren Commission's pathologists and subsequent independent forensic reviews have generally supported this.
• No credible eyewitness identified an individual crouching or firing behind the fence during the shooting itself.
• No credible physical evidence of a shooter's firing position has been located in the decades since.

NARA Declassifications (2017–2023)

In compliance with the JFK Records Collection Act, the National Archives has released tranches of previously classified documents in 2017, 2018, 2021, 2022, and 2023. None of the released documents have produced documentary evidence establishing a second shooter at the grassy knoll or identifying a shooter by name. Some documents confirmed prior known facts about CIA and FBI equities in the investigation and disclosure decisions. The declassifications have fuelled ongoing interest but not produced the "smoking gun" for any specific sub-theory.

The Warren Commission vs. the HSCA

The evidentiary record leaves two official competing conclusions:

• Warren Commission (1964): Oswald acted alone. No credible evidence of a second shooter.
• HSCA (1979): Probable conspiracy involving at least two gunmen, based on the acoustic evidence.
• NRC (1982): Acoustic evidence rejected; the impulse was recorded after the shooting.

The scientific consensus following the NRC review is that the acoustic evidence that drove the HSCA conclusion is not reliable. The Warren Commission conclusion — one shooter, Oswald — therefore remains the better-supported position on the current evidence, though "better-supported" does not mean fully resolved.

Why the Claim Persists

The grassy knoll claim combines several factors that make conspiracy framings durable:

• The original acoustic analysis appeared to provide scientific validation of the intuition that there was a second shooter.
• The physical setting of Dealey Plaza does look like a natural firing position.
• Some genuine institutional failures — CIA and FBI withheld relevant information for decades — created an environment of justified scepticism about official accounts.
• Kennedy's assassination remains emotionally and culturally significant enough to sustain popular interest in alternative explanations.

None of these factors constitute evidence of a second shooter.

Verdict

Unsubstantiated. The primary evidentiary basis for the grassy knoll claim (the Dictabelt acoustic analysis) was rejected by the NRC and FBI. No physical evidence of a second shooter — no bullet, no casings, no confirmed firing position — has been produced. Witness testimony is mixed and unreliable as to direction of fire. The HSCA's 1979 "probable conspiracy" conclusion rested on the acoustic evidence the NRC subsequently invalidated. The claim is unsubstantiated but, given the passage of time and the partial document record, not fully resolvable.