Analyses

Three formal studies constitute the mainstream forensic record on the Zapruder film: the FBI's 1963–64 laboratory work for the Warren Commission, the Itek Corporation's 1976 study commissioned by CBS News, and the HSCA Photographic Evidence Panel's 1978 work.

Itek (1976). Photogrammetrists Frank Scott and Charles Wyckoff conducted a frame-by-frame geometric analysis using Dealey Plaza survey data. They concluded that the trajectory of the first non-missed shot was consistent with an origin at the Depository's southeast sixth-floor window, and that the head-shot trajectory at Z-313 was also consistent with that origin — but they explicitly noted that the head-shot geometry cannot exclude a shot from the general direction of the Dal-Tex Building.

HSCA Photographic Panel (1978). The 22-member panel confirmed the film's authenticity, corroborated the Itek geometry, and identified the "jet effect" — a rearward head movement caused by the forward expulsion of tissue — as physically plausible for a shot from behind. The panel did not claim to have proven the shot direction from the film alone (HSCA Report, vol. 6, sec. IV).

Two working historians stand out for producing peer-cited, document-driven dissent that stays within the boundaries of the evidence.

Josiah Thompson, Six Seconds in Dallas (1967) and Last Second in Dallas (2021). Thompson, a philosophy professor and later a licensed investigator, was retained by Life to study the film in 1966. His 1967 book proposed a three-shooter scenario based on frame-by-frame head-motion analysis. His 2021 book revisits the acoustic evidence with new expert analysis and argues that the head-shot dynamics visible at Z-312 through Z-315 are best explained by nearly simultaneous shots from the rear and the right-front. Thompson's methodology is contested; his sourcing is meticulous.

David Wrone, The Zapruder Film: Reframing JFK's Assassination (2003). Wrone, a professor of history at the University of Wisconsin, produced the most complete published chain-of-custody study of the film. He rejects the alteration hypothesis on documentary grounds and argues that the film, read carefully, is incompatible with the single-bullet theory. His book is the standard citation for the film's documentary history.

A separate literature — most prominently David Lifton's Best Evidence (1980), Jack White's frame-by-frame work, and Doug Horne's Inside the ARRB (2009) — argues that the film held at NARA is not the camera-original but a substitute fabricated at the CIA's NPIC facility on the weekend of November 23–24, 1963. The hypothesis rests primarily on the McMahon and Hunter recollections recorded by the ARRB in 1997.

The alteration hypothesis is rejected by Kodak's Roland Zavada in his 1998 ARRB report and his 2009 addendum, by David Wrone, and by Josiah Thompson. It is a minority position within the researcher community and is not accepted by any federal body that has examined the physical film. We present it here because it is the most frequently encountered claim of "cover-up," and readers deserve to know the actual state of the evidence for and against it.

A large volume of popular writing — YouTube analyses, self-published books, message-board threads — makes claims about missing frames, painted-in occupants, and doctored backgrounds. Almost none of it engages with Zavada's optical analysis, with the physical characteristics of Kodachrome II reversal stock, or with the documented chain of custody. We do not catalog these claims. Where a specific popular claim intersects credentialed research — for example, the "black patch" on the back of Kennedy's head — we treat it under the relevant analytical section above.