CRITIQUE OF DONALD B. THOMAS’ ANALYSIS OF PHOTOGRAPHIC EVIDENCE RELATED TO THE ACOUSTIC EVIDENCE
In March, 2001, Science & Justice, a quarterly publication of Britain’s Forensic Science Society, published a paper by Donald B. Thomas, an entomologist  and part-time assassination researcher working for the U.S. Department of Agriculture’s Subtropical Agricultural Research Laboratory in Weslaco, Texas. Thomas became convinced of a conspiracy in the Kennedy assassination after viewing Oliver Stone’s 1991 motion picture, JFK.
In his Science & Justice research paper, Thomas claimed that the 1982 Committee on Ballistic Acoustics’ (CBA) report debunking the HSCA acoustic evidence was flawed and that a statistical review of the HSCA acoustic work confirmed their findings and elevated the probability of a grassy knoll shot from 95 to 96%. Thomas also claimed that five shots, not four as the HSCA had concluded, had been fired in Dealey Plaza. 
Thomas’ 2001 research paper and his subsequent writings and speeches on the subject, resulted in renewed debate about the validity of the HSCA’s acoustic evidence of conspiracy. While Thomas supported the HSCA’s conclusion that the assassination of President Kennedy was the result of a conspiracy, his own acoustic findings were at odds with virtually every acoustic conclusion reached by the HSCA about the shooting in Dealey Plaza.
First, Thomas believed that five shots, not four as the HSCA had concluded, were fired in Dealey Plaza. Second, Thomas believed that the five shots fired in Dealey Plaza were fired at times different than those specified by the HSCA. Third, Thomas believed that at least three gunmen, not two as the HSCA concluded, were firing at the president’s motorcade. Fourth, Thomas believed that the fatal head shot was fired from the grassy knoll; while the HSCA concluded that a grassy knoll shot must have missed the motorcade entirely. 
Since the photographic record proves that the acoustic evidence utilized by Thomas and the HSCA to support a conspiracy is invalid, the following section focuses on additional errors and omissions in Thomas’ photographic analysis which he offered in support of the acoustic evidence, and hence, a conspiracy in the assassination of President Kennedy.
Many of Thomas’ claims were factoids with little or no basis in fact. The following four assertions are addressed in no particular order of importance:
(SEC-1) THOMAS’ PROPOSED RE-TIMING OF THE FIRST SHOT FAILS TO PROVIDE OFFICER McLAIN SUFFICIENT TIME TO TRAVERSE THE DISTANCE REQUIRED FOR THE ACOUSTICS EVIDENCE TO BE VALID.
Thomas concluded in his 2001 presentation, “Hear No Evil: The Acoustical Evidence in the Kennedy Assassination,” that the first shot was fired at the equivalent of Zapruder frame Z175, not Z160 as designated by the HSCA. 
The proposal that the first shot was fired 0.82 seconds later than the HSCA hypothesized raises the question of whether a re-timing of the first shot would alter the conclusions drawn from the photographic record and presented in this document.
In other words, if McLain was indeed the officer with the open microphone and had an additional 0.82 seconds (for a total of 1.37 seconds) available to him to traverse the 174.38-foot distance between his last known location at the corner of Main and Houston and the microphone position dictated by the acoustic evidence, could McLain have made it to the microphone position in time to transmit the sound of the first shot at Zapruder frame Z175?
The answer is, no. As this paper has already demonstrated, McLain’s last known position depicted in Hughes frame H648 is the equivalent of Zapruder frame Z150 (+/- one frame). If the first shot was fired at Z175, as suggested by Thomas, McLain would have 1.37 seconds (175 – 150 = 25 frames ÷ 18.3 fps = 1.37 sec) to traverse the 174.38-foot distance between his last known location and the microphone position dictated by the acoustic evidence. In order to accomplish this feat, McLain would have to travel at a speed significantly greater than the maximum speed attainable using the motorcycle McLain was riding.
McLain’s Harley-Davidson motorcycle was capable of a top speed of 95 mph. While McLain might have been able to cover the 174.38-foot distance in question in the allotted time at an average a speed of 86.8 mph (174.38 ft ÷ 1.37 sec = 127.3 ft/per/sec = 86.8 mph), there are two other important factors that must be considered.
First, McLain’s last known speed as depicted in the Hughes film was 14.7 mph. [See Appendix II, McLain in the Dorman Film, p.90] Second, the acoustic evidence dictates that the officer with the open microphone was moving at a speed of 10.5 mph between shots one and two.  Consequently, McLain would have to accelerate from a speed of 14.7 mph to a speed much greater than an average speed of 86.8 mph, then decelerate to 10.5 mph over the course of the 1.37 seconds available to him. How much greater than 86.8 mph would McLain have to travel down Houston Street?
Using computer models and a spline velocity curve, it was determined that McLain would have to accelerate to a speed of over 452.76 mph – more than half the speed of sound – in just 0.5 seconds in order to traverse the 174.38 foot distance in the allotted time and still match the known in and out speeds dictated by the Hughes film and the acoustic evidence. In short, it would be physically impossible for the Harley-Davidson motorcycle which McLain was riding to perform such a feat.
Setting aside the physical impossibility of such a feat, there is one common sense reason that weighs against the conclusion drawn by Thomas:
What possible motivation could McLain have for leaving his assigned position in the motorcade, the position he has occupied for the entire motorcade, and accelerate to a point nearly 180 feet forward of that position before any shots were fired? The reader will recall that the period under discussion is the 1.37 seconds before any shots were fired at the motorcade. Thomas’ argument fails to offer a logical reason for this inexplicable action.
(SEC-2) THOMAS’ PROPOSED TRAJECTORY AND SPEED FOR THE OPEN MICROPHONE FAILS TO SYNCHRONIZE WITH THE DALLAS POLICE RECORDING OR THE PHOTOGRAPHIC RECORD.
The radio transmission received from the motorcycle with the open microphone and recorded by the Dallas police demonstrates that the engine of that motorcycle was running at a constant rate during the two minutes prior to the impulse sounds designated as gunshots by the HSCA acoustic
The first indication of a change in that constant rate occurs just 3 seconds before the impulse sounds thought to be “gunshots” are heard. At that time, the motorcycle engine slows down to about one-quarter of its previous rate. The motorcycle engine sounds continue at this lower rate for a period of about thirty seconds, then gradually increase in volume until they reach a maximum level equal to about 75% of the constant rate heard prior to the impulse sounds.
Thomas and the HSCA believed that the initial constant rate, the slowing of the engine and the gradual increase in rate corresponds to McLain’s suspected approach to the Elm and Houston corner, his slow glide down Elm Street, and his eventual acceleration out of Dealey Plaza. Thus, Thomas and the HSCA believed the engine sounds are consistent with and supportive of the hypothesis that the open microphone was in fact in Dealey Plaza and transmitted the sounds of gunfire.
However, there are numerous conflicts between the recording and the known progression of the motorcade before, during, and after the shooting that destroy the contention that the motorcycle with the open microphone was in the motorcade, and therefore, in a position to transmit the sounds of “gunshots.” Three instances of conflict immediately come to mind:
First, the Dallas police recording does not contain any auditory evidence of the kind of changes in engine rate that we know occurred during the two minutes prior to the shooting. For instance, we know the motorcade traveled down Main Street at a rate much slower than the average speed of 11.3 mph estimated by the FBI for the shooting sequence. Estimates by some motorcade officers put the speed on Main Street as low as 6 to 8 mph. News films clearly show this to be true and many officers testified to this fact. During the period on Main Street, the motorcycle escorts were also known to occasionally rev-up their engines in short bursts. Yet, there is no evidence of any of this on the audio recording which begins 2 minutes before the alleged gunshot sounds.
Second, we know from the photographic record that McLain accelerated to 14.7 mph as he rounded the corner from Main onto Houston – changing speed in order to maintain his position in the motorcade – yet, again, we don’t hear any evidence of this change in speed in the recording.
Third, even the Thomas\HSCA scenario dictates that McLain had to accelerate to an average speed of 17-20 mph (twice the average speed of the motorcade) as he traveled north on Houston Street in order to gain ground on the presidential limousine and make it to the position predicted by their acoustic analysis in time to transmit the sound of the first shot.  Yet, once again, we don’t hear any evidence of this change in speed on the recording. Instead, the recording shows the motorcycle engine to be running at a constant rate with no change in apparent speed.
If the motorcycle and open microphone are in fact part of the motorcade as Thomas alleges, why is there is no evidence of any of these events on the audio recording?
The conflicts between the Thomas\HSCA scenario and the acoustic recording are not limited to the moments leading up to the impulse sounds thought to be shots. Serious conflicts continue even after the supposed “shots” are fired.
For instance, the HSCA calculated that the open microphone was moving at a speed that was consistent with the average speed of the presidential limousine – 11.3 mph – at the time of the shooting. Both Thomas and the HSCA considered this fact significant. Thomas explained, “This is an impressive coincidence…Thus, the topographic order in the matching data is in remarkably close accord with the working hypothesis that a police motorcycle with an open microphone was traveling in the motorcade, northerly on Houston Street and westerly on Elm Street at a speed of around 11 mph when the President was killed by gunfire.” 
Both Thomas and the HSCA make a serious error in using average speeds to conclude that the open microphone was in close correspondence with the actual speed of the motorcade. James C. Bowles, the Dallas police radio dispatch supervisor at the time of the assassination and author of “The Kennedy Assassination Tapes: A Rebuttal to the Acoustical Evidence Theory,” a 1979 rebuttal to the HSCA findings, explained the issue succinctly when he told author Larry Sneed, “The limousine was not driven at a constant speed. This is another one of the things that was an inherent error in the House Select Committee’s scientific analysis. They calculated that the motorcade ran at an average speed of about 11 mph. I can show places in the Zapruder film where it went faster or slower. It did not travel at 11 mph at a constant rate. You can’t make averages serve you like a master. It’s a point of reference. In this type of situation, you had to deal with each occurrence as a matter of fact at the time it occurred.” 
Computer analysis of the photographic record of the assassination sequence supports Bowles’ contention. The presidential limousine approached the Elm and Houston intersection at about 10.5 mph, slowed to 6.6 mph as it began the turn onto Elm Street, accelerated to 9.5 mph as it came out of the turn, and was traveling at about 10.5 mph when Zapruder began filming. The limousine was moving at 11.7 mph when Kennedy disappeared behind the Stemmons freeway sign, accelerating to 12 mph by the time it re-emerged from behind the sign. Suddenly, the limousine decelerated and was moving 8.9 mph at the time of the head shot.
Likewise, computer analysis shows other vehicles in the motorcade traveling on Houston Street at speeds varying from 7.1 to 9.9 mph as they follow the presidential limousine.
Computer analysis also shows McLain himself traveling at 14.7 mph as he rounds the turn from Main onto Houston (as seen in the Hughes film), slowing to 6.4 mph as he turns onto Elm Street (as seen in the Dorman film), and moving at 10.5 mph just before he leaves Dealey Plaza (as seen in the Bell film).
Even the Thomas scenario presumes that there were six variations in speed as the motorcycle with the open microphone made its way through Dealey Plaza. For instance, Thomas calculates that the open microphone accelerated to 17-20 mph as it traveled up Houston Street, slowed to 10.5 mph as the first shots were fired, sped up to 11.7 mph, slowed again to 11.0 mph for the fatal head shot, slowed again to an average speed of 4 mph  for nearly thirty seconds, and finally accelerated out of Dealey Plaza. 
Yet none of these measurable variations in speed are heard in the police audio recording. Instead of multiple variations in rate, the recording shows only two changes in rate – a single slowing, followed by a single acceleration. 
Why doesn’t the Dallas police audio recording reflect the constant acceleration and deceleration that the HSCA and Thomas insist occurred in Dealey Plaza?
The only reasonable answer is that the open microphone was not in Dealey Plaza. There are two reasons we know this is true. First, the 1982 National Research Council’s Committee on Ballistic Acoustics (CBA) reviewed the work of the HSCA’s acoustic team and concluded that the impulse sounds thought to be “gunshots” were actually recorded at least one minute after the assassination. Second, the photographic record conclusively demonstrates that no motorcycle was in a position to transmit the impulse sounds thought to be “gunshots.”
(SEC-3) THOMAS’ ACOUSTICAL SHOOTING SEQUENCE IS NOT SUPPORTED BY THE HSCA, THE TESTIMONY OF EYEWITNESSES, OR THE PHOTOGRAPHIC RECORD
While the acoustic experts hired by the HSCA determined that the Dallas police audio recording contained evidence of four gunshots, Thomas proposed that the Dallas police recording actually contains evidence of five shots. Thomas also claimed that the timing of the shots was different than the timing proposed by the HSCA. And most important of all, Thomas believed the fatal head shot was fired from the grassy knoll, not the Texas School Book Depository as the HSCA concluded. A necessary consequence of Thomas’ belief that the fatal head shot was fired from the grassy knoll is a re-ordered shot sequence that begins later than the sequence proposed by the HSCA.
Thomas asserted that “The close agreement between the time sequence of impacts seen in the Zapruder film and the time sequence of gunshots on the police audio tape provides a basis for a coherent reconstruction of the crime.” 
However, those intimately familiar with the assassination evidence know that Thomas’ shooting sequence is not in harmonious agreement, as he claimed, but completely at odds with the photographic record.
In 1979, the HSCA acoustic experts concluded that four shots were fired from two sources – the Texas School Book Depository (TSBD) and the grassy knoll (GK) – in the following sequence:
Thomas, on the other hand, asserted the following five shot sequence, which includes an inexplicable “noise” heard immediately before the shooting:
Thomas described these six events in the following manner:
Z146 – “Noise”
Thomas began his analysis by concluding that an inexplicable “noise” occurred at the equivalent of Zapruder frame Z146.  Thomas failed to determine what this “noise” was or where it came from, although he described the effect it had on Governor Connally.
Thomas wrote, “Beginning at frame 165 Governor John Connally, sitting directly in front of the President, makes a rapid head movement 90 deg to his left, then turns completely around in the opposite direction to glance back over his right shoulder. In his testimony to the Warren Commission the Governor stated that he turned to look back in response to hearing what he believed was a gunshot.” 
Anyone who consults the Zapruder film will see that Connally turns to his left in the range Z152-160; then begins a four-tenths of a second turn to his right beginning at Z163.  All of these actions end by Z170; they do not begin at Z165 as Thomas asserted. It is very important to note that Connally consistently testified that he turned to his right after hearing a rifle shot. Being an avid hunter, Connally was certain he had heard a gunshot – not an inexplicable “noise” as Thomas proposed – and believed that the rifle shot had come from over his right shoulder; hence his turn to the right.
Z175 – TSBD Shot
Thomas concluded that the first shot was fired at the equivalent of Zapruder frame Z175 and missed the limousine. Thomas claimed that the effects of that first shot can be seen in the Zapruder film a little more than a second later.
Thomas wrote, “In the sequence of frames 194 to 207 (at which point he disappears behind the sign) President Kennedy suddenly froze his waving hand and abruptly raised his right elbow which had been resting on the car windowsill. He then shook his head from right to left. During the same sequence, a young girl [Rosemary Willis] who had been running alongside the limousine, stopped abruptly and turned to look in the general direction of the Book Depository behind the limousine. Also during this sequence, Mrs. Kennedy, who was waving at the young girl, turned to look in the direction of the President.” 
Again, anyone consulting the Zapruder film will find Thomas’ description to be largely false. The president is looking hard over his right shoulder when he begins to turn back to his left at Z200; a turn that continues through Z207 when he disappears behind the Stemmons freeway sign. At that time, he is still facing to his right; a position he maintains until he emerges from behind the Stemmons sign. Thomas’ claim that Kennedy “shook his head from right to left” is a distorted version of the HSCA Photographic Panel’s account. They wrote that “during frames 200-202, [Kennedy’s] head moves rapidly from right to left,”  in the direction of his wife. But even the HSCA account is false. The president never turned to look at his wife before disappearing behind the Stemmons Freeway sign, as the HSCA reported.
How could the HSCA make such a mistake? By today’s standards, the 1978 HSCA panel was working with an inferior copy of the film. The Zapruder film frames available today in digital format are from the original source material and consequently are much clearer than those utilized by the HSCA. Thomas apparently repeated their error, adding his own set of distortions.
Thomas’s description of Mrs. Kennedy’s actions is equally false. First, the photographic evidence clearly shows that in the moments before the shooting Mrs. Kennedy never lifted her hand in a wave at anyone, let alone at Rosemary Willis, as Thomas suggested. Second, while Mrs. Kennedy does turn toward the president during the range Z190-200 (not Z194-207, as Thomas claimed), she had already turned to her right by Z185, and her reason for turning was very explicit. Mrs. Kennedy testified that she was looking to her left when she heard a “noise” that she thought was a backfire from a motorcycle; which was rather common during motorcades. Then suddenly, she heard Governor Connally yelling, ‘Oh no, no, no!’ And so she turned to her right. 
The Governor’s wife, Nellie, also testified that her husband yelled ‘Oh, no, no, no!’ immediately after the first shot.  The Governor himself couldn’t recall if he said ‘Oh, no, no, no!’ after the first or second shot; but did remember turning to look over his right shoulder after the first shot. 
The left-to-right actions of both Governor Connally and Mrs. Kennedy are seen in rapid succession between frames Z162 and Z185; first Connally turns (Z163-170), then Mrs. Kennedy turns toward Connally (Z168-185), and finally toward her husband (Z190-200). Both Governor Connally and Mrs. Kennedy are seen reacting exactly as they testified they did immediately after the first shot. This combined testimony, confirmed by the photographic record, is very powerful and supportive of a first shot prior to Z160.
What happened to the shot fired at Z175? According to Thomas, the bullet missed the limousine and possibly skipped on down toward the Triple Underpass where it wounded eyewitness James Tague.  Thomas also believed that “shrapnel” from this fragmented missed shot imbedded in the rear of the president’s skull and was later interpreted as such in the president’s x-rays. According to Thomas, this early “wounding” caused the president to “flinch” and shake his head back and forth and exclaim, “My God, I’m hit!” a statement attributed to him by Secret Service agent Roy Kellerman, who was riding in the front seat. According to everyone else in the car, the president said nothing during the shooting. 
Z204 – Rogue Shot
Thomas concluded that the second shot was fired at the equivalent of Zapruder frame Z204 and was fired by a second gunman located to the rear of the president’s motorcade; the exact location undetermined. Hence, Thomas called this the “rogue shot.”
Thomas wrote, “This shot seems to have caused Phil Willis to flinch, depressing his shutter button and exposing his famous photograph of the President’s limousine. However, because this shot occurs so close following the first shot, and so soon before the next shot, it could not have come from Oswald’s rifle, according to the U.S. Army Weapons Testing Branch. This is the rogue shot. I am unaware of any evidence that would support the hypothesis that a rogue bullet caused any wounds.”  In short, Thomas believed that this shot also missed the motorcade.
Where did the so-called “rogue shot” go, and who fired it? Thomas doesn’t seem to know, stating, “We really don’t know where it went. We don’t know where it came from.” 
It is difficult to accept Thomas’ analysis given that his so-called “rogue shot” corresponds to the HSCA’s second shot which they concluded, based on the acoustic evidence, was fired from the southeastern most corner window of the sixth floor of the Texas School Book Depository. Their acoustical proof was three correlations with test shots fired from that location.
Thomas rejected their conclusions for two reasons. One, Thomas erroneously believed that Oswald’s rifle could only be fired once every 2.25 seconds. However, this is a fundamental misrepresentation of the facts. The 2.25 second figure comes from early FBI and Army tests in which subjects timed the firing of the rifle using only the scope. Tests conducted by the HSCA, however, proved that the rifle could be fired in 1.66 seconds using the iron sights rather than the scope.  Second, there is no obvious, observable indication of a shot being fired at Z204 of the Zapruder film. According to Thomas, either the shot missed or no shot was fired at all. Thomas embraced the latter, which enabled him to claim that a second gunman was firing at the president from behind. 
Moreover, Thomas’ claim that a shot fired at Zapruder frame Z204 caused Phil Willis to take his “famous photograph” couldn’t possibly be true. The Willis photograph that Thomas refers to is Willis slide No.5, which the HSCA photographic panel determined was exposed at the equivalent of Zapruder frame Z202 – one tenth of a second before Thomas’ proposed shot. 
Z224 – TSBD Shot
Thomas concluded that the third shot was fired at the equivalent of Zapruder frame Z224 and struck both Kennedy and Connally – the single bullet.
Thomas’ acoustic evidence for the shot at Z224 is a test shot correlation rejected by the HSCA. In his final report, Dr. James Barger of Bolt, Beranek and Newman, Inc., wrote that this particular test correlation was determined to be a false alarm (i.e., not a real shot) “because it occurred only 1.05 sec later than earlier correlations also obtained from the TSBD. The rifle cannot be fired that rapidly. Since there are three correlations plausibly indicating the earlier shot, the one occurring 1.05 sec later must be a false alarm.” 
Why does Thomas accept what acoustic experts rejected? Thomas wrote that Professor G. Robert Blakey, the former chief counsel for the Assassinations Committee, and Dr. James Barger told him that HSCA members would have been “more easily convinced of the acoustics evidence if there were not a rogue shot. Dr. Barger admitted to me that the criteria for judging a ‘false alarm’ in this instance was ‘ad hoc,’ – which is Latin for ‘bull-oney.’ Some matches were judged to be false alarms because it would require an unrealistic microphone trajectory. That is not the case for the third [shot]. On the contrary, it falls exactly into the order required by the working hypothesis.” 
Thomas failed to acknowledge that it is his own reshuffling of the shooting sequence which leaves him without an acoustic shot to match up with the Zapruder film evidence of a single bullet hit at Z224 – an obvious bullet hit, second only to the obvious hit at Z313. In order to maintain his belief that the fatal head shot was fired from the grassy knoll, which very forensic pathologist who has studied the case rejects, Thomas was forced to find acoustic evidence of the single bullet hit that clearly occurred at Z224. Consequently, Thomas, who has no expertise in acoustic science or forensic pathology, resurrected a test correlation that was rejected by acoustic experts.
It should be understood that Thomas’ ad hoc reasoning is not limited to the acoustic aspects of the assassination. For instance, although Thomas concedes that a single bullet could have gone through Kennedy and hit Connally,  he rejected the idea that Commission Exhibit (CE) 399 – the so-called “magic bullet” was the bullet responsible for the seven wounds produced in both men. Instead, Thomas postulated that CE567, one of the bullet fragments found on the floor of the limousine the night of the assassination and linked to the fatal head wound was actually a fragment of the single bullet that struck Kennedy and Connally at Z224. 
Since CE567 was traced to Oswald’s rifle to the exclusion of all other weapons, and Thomas rejected the forensic evidence that proves Kennedy’s fatal head wound came from behind, as well as the Warren Commission and HSCA conclusions that Oswald fired that fatal shot; Thomas was forced to link that bloody fragment to another wound – hence, Thomas’ conclusion that CE567 was actually the result of the single bullet hit at Z224.
Thomas didn’t explain how CE567 escaped Connally’s left thigh and ended up on the floor of the front seat of the limousine.
Z312 – Grassy Knoll Shot
Thomas concluded that the fourth shot was fired at the equivalent of Zapruder frame Z312 and struck Kennedy in the head. This fatal shot was, according to Thomas, fired from the grassy knoll – a conclusion rejected by every forensic medical panel that has ever reviewed President Kennedy’s authenticated autopsy photographs and x-rays. Even forensic pathologist Dr. Cyril Wecht, an outspoken critic of the Warren Report and a supporter of a conspiracy in the Kennedy assassination, acknowledged that the photographs and x-rays conclusively show that the president was struck by a single shot, fired from the right rear of the limousine; not the grassy knoll located to the limousine’s right front.
While the HSCA believed that a shot had been fired from the grassy knoll (based on the acoustic evidence, which has since been shown to be invalid by the 1982 Committee on Ballistic Acoustics and this analysis of the photographic record), they concluded that the shot was fired one-half second before the fatal head shot and that it missed the motorcade. They reached this conclusion after their forensic medical panel determined that there was no forensic support for a grassy knoll hit. Thomas, who has no expertise in forensic pathology, rejected their logic.
Blur Analysis Support for a Grassy Knoll Gunman?
Thomas largely based his proposed fatal grassy knoll shot on a re-evaluation of the “jiggle” or blur analysis conducted by the HSCA. The blur analysis theorizes that camera ‘jiggles’ caused by the natural human startle reaction to gunfire are responsible for many of the blurs seen in the Zapruder film. Thomas asserted that blurs seen concurrent with the fatal head shot begin too soon to have been caused by a startle reaction to a shot fired from the Texas School Book Depository, which was 265 feet away from Zapruder’s location. Simply put, the sound of a shot fired from the Depository could not have reached Zapruder in the time between its firing and Zapruder’s startle reaction, given the distance to Zapruder’s location. Thomas reasoned that the shot that caused the head shot blurs in Zapruder’s film must have been fired from a position closer to Zapruder; hence Thomas’ conclusion that the fatal shot was fired from the grassy knoll, just 53 feet from Zapruder’s location. 
While ‘blur’ analysis has some basis in scientific fact (auditory-based startle reactions can cause blurs in filmed images), Thomas and others who have used ‘blur’ analysis to determine how many shots were fired in Dealey Plaza, fail to consider non-auditory sources as the cause of at least some of the blurs seen in the Zapruder film.
There are two possible non-auditory sources that might have produced blurs or ‘jiggles’ in the Zapruder film – erratic camera operation and a natural human reaction to visual stimulus.
First, the mere act of holding and operating a motion picture camera, especially one equipped with a telephoto lens, can cause the kind of jiggle or blurs seen in the Zapruder film. For instance, we know that Zapruder could not have filmed the president’s passing limousine from a stationary position. In order to cover the nearly 180 degree of exposed roadway, Zapruder would had to have repositioned his feet and twisted his torso as the limousine drove by. Any slight shuffling of his feet or shift in body position could easily have resulted in the kind of jiggles or blurs we see in the film. 
In addition, Zapruder’s secretary, Marilyn Sitzman, was standing with Zapruder on the concrete pedestal. Zapruder had a sense of vertigo and Sitzman stood behind him to steady him; which means, of course, that Sitzman’s body was in contact with Zapruder. Any interaction between the two as Zapruder pivoted to film the passing motorcade could also have resulted in jiggles or blurs in the resulting film.
Second, the visual record itself can also serve as a possible source of jiggle or blurs. For instance, there are some erratic camera movements that occur when the president’s limousine disappears behind the Stemmons freeway sign. Zapruder, tracking the limousine with his camera, hesitates in panning his camera as the limousine disappears from view, then resumes following the limousine as it reappears from behind the sign. The result is one of the larger jiggles or blurs in the film.
Another visual jolt, surely capable of causing erratic camera movements, occurs at the moment of the head shot. Zapruder testified to being horrified by what he saw through the telephoto viewfinder.
While gunshots can cause startle reactions resulting in film blurs, so can other non-auditory sources. Consequently, it is impossible to say with any degree of certainty that a particular set of film blurs were caused by gunshots as opposed to erratic camera movements, visual stimulus, or any number of other non-auditory sources.
Eyewitness Support for a Grassy Knoll Gunman?
Thomas claimed that a grassy knoll shot was supported by the “majority” of eyewitnesses; writing, “Many witnesses, one of them Abraham Zapruder, testified to the Warren Commission that they thought the shot originated from the area known as the Grassy Knoll…Some individuals reported seeing a man with a .30-30 rifle running from the scene of the assassination.” 
In reality, less than 12% of eyewitnesses thought the grassy knoll was the source of the shots. The HSCA reviewed the statements of 178 witnesses to the shooting. The results show that out of a majority who could establish a direction at all, a majority of 49 of them (27.5%) thought the shots came from the Book Depository, a minority of 21 (11.8%) thought they came from the grassy knoll, 30 (16.9%) thought they originated elsewhere, and 78 (43.8%) were unable to tell which direction the shots had been fired from. 
Thomas’ five shot proposal has even less support from eyewitnesses. Less than 7 out of 178 eyewitnesses (4%) who gave statements believed that more than four shots had been fired. Thomas claimed five shots were fired. The vast majority, 132 out of 178 (74%), reported hearing only 3 shots. 
Thomas’ assertion that Zapruder pointed to the grassy knoll as the source of the head shot is equally misleading. Zapruder made it clear that he did not know which direction the fatal shot came from. Twice Zapruder said, ‘No,’ when asked if he had an impression as to the direction the shots were fired from. He did say that when police ran into the area behind him he “assumed” the shots came from there; but that was an impression based on the actions of police and not on the sound as he heard it. According to Zapruder, “there was too much reverberation.” Zapruder added that he wasn’t even sure the first sound he heard was a gunshot. Only after the president’s head exploded with the sound of the second shot did Zapruder realize that the sounds were gunshots. 
Zapruder also testified that the first shot was fired and he saw the president “lean over and grab himself,” a reference to Z225 of his film.  Zapruder then said that before he had a chance to organize his thoughts he “heard a second shot” and saw the president’s head explode.  Zapruder doesn’t recall hearing a third shot.
Thomas’ suggestion that “some individuals reported seeing a man with a .30-30 rifle” running from the grassy knoll is completely false. The citation Thomas provided to support his claim is a page from the Channel One transcript of the Dallas police radio recordings. The transmission cited is a description of the Texas School Book Depository gunman who was seen firing what was described as a “30-30 rifle” from the southeastern-most corner window of the sixth floor. There are no credible eyewitness accounts that support a grassy knoll gunman, nor was any physical evidence establishing the presence of a grassy knoll gunman ever recovered.
Z326 – TSBD Shot
Thomas concluded that the fifth and final shot was fired at the equivalent of Zapruder frame Z326 and missed the motorcade entirely.
In a 2006 interview, Thomas stated, “I’m pretty sure that’s the one that went over the limo and hit the grass over by the manhole cover over nearby where Tague had been standing. This is the one that the witnesses said the police came over and someone dug a - claimed that they’d taken a bullet out of the grass. In fact, it was the day after, on Saturday that Carl Day, the forensic bureau fellow for the Dallas Police Department went out with a tape measure and measured the distance from the Book Depository to that spot. When reporters asked him what he was doing he said, ‘Well, this is a place where we recovered a bullet.’ So, I always figured that was the bullet they dug out of the grass, and was probably Commission Exhibit 399.” 
Thomas’ statements are false and misleading. The manhole cover Thomas referred to was actually located along the south Elm Street curb, not the Main Street curb where eyewitness James Tague was located. The Dallas police denied that a bullet was recovered from the area of the Elm Street sewer cover, nor has any eyewitness, photograph, or film ever surfaced that supports this factoid that appears in some of the earliest assassination literature. Finally, the claim that Dallas police crime lab Lieutenant J. Carl Day told reporters he recovered a bullet near the manhole is another second hand factoid without any basis in fact. In fact, Day told author Larry Sneed, whose book Thomas cites elsewhere in his research paper, that “they found nothing” where a bullet reportedly struck. 
In his presentation Hear No Evil: The Acoustical Evidence in the Kennedy Assassination, Thomas concluded that “the sequence of gunshots identified by the acoustical evidence meshes closely with the sequence of victim reactions, including impacts, seen in the Zapruder film.” 
Nothing could be further from the truth. Thomas had concocted a conspiracy theory in the Kennedy shooting by reshuffling acoustic evidence, ignoring the medical record, and misrepresenting the photographic record.
(SEC-4) THOMAS’ PHOTOGRAPHIC ANALYSIS CONTAINS FIVE CRUCIAL ERRORS.
Don Thomas made several attempts to find harmony between the photographic record and his belief that Dallas police officer H.B. McLain was in a position to transmit the sound of gunshots from Dealey Plaza, and thus, validate the acoustic evidence of conspiracy.
As this paper has already demonstrated, the photographic record shows conclusively that McLain could not have been in a position to transmit the sounds of gunshots, nor could any other motorcyclist in the motorcade, and consequently, the acoustic evidence of a conspiracy is invalid.
This section documents five crucial errors that Thomas made in his photographic analysis:
(1) Camera Car 1 is 15 feet in length.
Thomas reported that Camera Car 1, a 1964 Chevrolet Impala, was 180 inches (15 feet) in overall length, citing the 1964 Chilton’s Automotive Manual (the specific page was not mentioned). This is false.
The 1964 Impala had an overall length of 209.9 inches (17.5 feet). 
(2) Camera Car 1 is on a line-of-sight drawn between the Hughes’ camera and the northwest corner of the Records Building at Hughes frame H633.
Thomas reported that Camera Car 1 lies on a line-of-sight drawn between the Hughes camera  and the northwest corner of the Records Building in Hughes frame H633.  This is false.
Enlargements of Hughes frame H633, created from the original source material archived by the Sixth Floor Museum, Dallas, Texas; clearly shows Camera Car 1 to be north of a line-of-sight drawn between the Hughes camera position and the northwest corner of the Records Building.
The true position of Camera Car 1 was determined by using computer models to align a model of the 17.5-foot-long 1964 Chevrolet Impala with Hughes’ field-of-view. The result shows the right rear bumper of Camera Car 1 is 2.95 feet north of, and 0.66 feet west of the line-of-sight drawn between the Hughes’ camera and the northwest corner of the Records Building; not on the line of sight as Thomas reported.
(3) Camera Car 1 traverses 73 feet between Hughes frame H633 and Zapruder frame Z220.
Thomas claimed that Camera Car 1 traveled 73 feet between Hughes frame H633 and Zapruder frame Z220. This is false.
Thomas’ two previous errors (using an overall car length of 15 feet, rather than the correct length of 17.5 feet; and positioning the car on a line of sight between the Hughes camera position and the NW corner of the Records Building; rather than slightly north and west of that line) resulted in an incorrect measurement for the distance Camera Car 1 traveled between Hughes frame H633 and Zapruder frame Z220.
When correctly scaled computer models of Camera Car 1 are aligned to Hughes frame H633 and Zapruder frame Z220, the distance between those two exposures was determined to be 59.8 feet; not 73 feet as reported by Thomas.
(4) Camera Car 1 traverses its own length in 21 frames (Z216-236) which calculates to a speed of 12.5 feet/sec (8.5 mph).
Thomas reported that Camera Car 1 traversed its own length (incorrectly described as 15 feet in length) between Zapruder frames Z216 and Z236 – a total of 21 frames. Thomas subsequently calculated that Camera Car 1 was traveling at 12.5 feet/sec (8.5 mph). Both of these calculations are false.
To determine the true speed of Camera Car 1 at approximately Z220; digital enlargements of the appropriate area of the Zapruder film were contrast enhanced and stabilized. It was determined from this enlarged and stabilized sequence that Camera Car 1 traversed its own length (established as 17.5 feet in length) between Z213 and Z236 – a total of 23 frames. Therefore the actual speed of Camera Car 1 at approximately Z220 was 13.89 feet/sec (9.5 mph).
(5) Camera Car 1 traverses the 59.8 feet between Hughes frame H633 and Zapruder frame Z220 in an estimated 6.2 to 8.3 seconds.
Thomas guessed that Camera Car 1 traversed the distance between Hughes frame H633 and Zapruder frame Z220 (incorrectly reported by Thomas as 73 feet in length) in 6.2 to 8.3 seconds based on the idea that Camera Car 1 was “most likely at or close to maximum speed” in the middle of the block between Main and Elm. This guesstimate is neither scientific nor accurate.
In order to determine the correct time interval between Hughes frame H633 and Zapruder frame Z220; the speed of Camera Car 1 prior to Hughes frame H633 was calculated based on the speed of the vehicle as seen in Hughes frames H614 to H631 – the sequence immediately before the one in question. Using computer models and visual inspection of the film itself, it was determined that Camera Car 1 was traveling at 11.83 feet/sec (8.1 mph) between H614 and H631.
Considering that the known speed prior to Hughes frame H633 was 11.83 ft/sec (8.1 mph) and the known speed at Zapruder frame Z220 was 13.89 feet/sec (9.5 mph), it was determined that Camera Car 1 was traveling at an average speed of 12.86 feet/sec (8.8 mph)  and therefore traversed the 59.8 foot distance between Hughes frame H633 and Zapruder frame Z220 in 4.65 seconds; not the 6.2 to 8.3 second guesstimate ventured by Thomas.
Consequence of Thomas’ Accumulated Errors
The five errors Thomas made in his calculations led him to conclude that Hughes frame H633 was exposed 3.8 to 5.9 seconds before the time of Thomas’ first acoustic shot;  the equivalent of somewhere between Zapruder frames Z67 and Z106. 
If Thomas had not made these five errors, he would have realized that Hughes frame H633 was actually exposed 2.19 seconds before the time of his first acoustic shot; and therefore was the equivalent of Zapruder frame Z135. This means that the last Hughes frame showing McLain – H648 – is the equivalent of Zapruder frame 150.
As already shown, the synchronization of Hughes frame H648 to Zapruder frame Z150 invalidates the acoustic evidence regardless of whether one accepts the HSCA’s conclusion that the first shot was fired at Z160, or Don Thomas’ own conclusion that the first shot was fired at Z175. In either case, no motorcycle could have been in the position dictated by the acoustic evidence to transmit the sound of “gunfire.”
Additional Errors, Omissions, Misleading Statements and Contradictions
In his 2001 research paper, Thomas criticized Greg Jaynes’ 1997 photographic presentation which synchronized Hughes frame H633 with Zapruder frame Z160 based on the angle of the seventh car in the motorcade, the Vice-Presidential Secret Service Follow-Up Car, as it turned onto Elm Street. Jaynes’ analysis was the result of simply “eyeballing” the Hughes and Zapruder films and had no geometric or scientific basis.
Thomas wrote that the H633/Z160 synchronization was “probably not correct.” Why? Thomas explained that the seventh car  in question probably “began its turn prior to the point where it came into view of Zapruder’s lens, and then because of the sharpness of the turn, had to make a second steering adjustment while in the intersection that is seen in the Zapruder film.” 
Of course, Thomas’ assertion has no basis in fact and defies common sense. The Secret Service car is following close to the rear bumper of the Vice-President’s car, as depicted in both the Hughes and Zapruder films. What possible reason would the driver of the Secret Service car have for pulling out of line and beginning the Houston to Elm turn before the Vice President’s car immediately in front of him does? Thomas’ explanation is a poor attempt to explain away an obvious problem – visual evidence that the Hughes and Zapruder films overlap or nearly overlap; which, of course, eliminates McLain’s opportunity to get to the first shot position in time to transmit the sound of “gunfire.”
In an effort to support his belief that McLain had enough time to get to the first shot position, Thomas used Camera Car 1, the tenth car in the motorcade,  to calculate the correspondence between the Hughes and Zapruder films. Thomas concluded that the tenth car traveled 73 feet in 6.2 to 8.3 seconds (6 to 8 mph) between the exposure of Hughes frame H633 and Zapruder frame Z220. This meant that McLain had 3.8 to 5.9 seconds to get to the first shot position; time enough to cover the 180 foot distance traveling at an average speed of 20.8 to 32 mph.  After Thomas factored in the accordion effect (i.e., the motorcade procession’s tendency to bunch up at corners and stretch out between blocks), he imagined that “McLain’s position in [H633] is likely closer to six or seven seconds prior to the first shot, in accord with Hughes’ memory that the shots occurred [five] seconds after he stopped filming.”  Consequently, Thomas believed that Hughes frame H633 synchronized to Zapruder frame range Z47 to Z65; not Z160 as the early analysis estimated.
It’s already been shown that Thomas made five serious errors in his analysis of the movements of Camera Car 1. [See above]
Thomas claimed in Emendation that his alignment of the Hughes and Zapruder films was supported by newsreel film shot by cameraman Malcolm Couch. Thomas noted that Couch, who was in Camera Car 3, the twelfth car in the motorcade;  filmed McLain approximately 200 feet west of the tenth car’s position at Elm and Houston. Thomas reasoned that “in the time it took [Car 12] to travel 200 feet from Main to Elm, McLain had traveled 400 feet. Therefore, [McLain’s] average speed during the interval has to have been twice whatever [Car 12] was doing.”  Thomas calculated that Camera Car 3 was averaging 7 mph as it traveled north on Houston Street, while he estimated McLain’s speed at 25 mph during the same period. Thomas concluded that McLain’s estimated speed of 20-25 mph was therefore “in accord with both the acoustical and the filmed evidence.” Thomas cautioned, however, that “these values are soft values, which is to say, they are inferences from observed data, not actual measurements, and therefore do not prove that McLain was in the right position to record the shots, only that he reasonable could have been.”
However, Thomas made a serious mistake in his analysis of the filmed record from which he then drew an erroneous conclusion. Thomas’ reasoning that McLain must have been averaging twice the speed of Camera Car 3, based on McLain’s position in the Couch film, assumes that both vehicles were constantly moving during the interval in question. In fact, they were not – Camera Car 3, the vehicle containing Couch, had come to a stop in front of the Texas School Book Depository about 6 seconds after the fatal head shot and remained there for approximately 15 seconds before continuing down Elm Street.
This fact is evident in the film made by Dave Wiegman, Jr., who was riding in Camera Car 1, two cars ahead of Couch. Wiegman was rolling film as the fatal head shot rang out. Six seconds later, Camera Car 1 stopped in front of the Depository and Wiegman jumped from the car, camera still rolling, and dashed on foot toward the pergola north of Elm Street. Fifteen seconds later, Malcolm Couch began filming from the rear seat of Camera Car 3. As he panned to his left, Couch captured Camera Cars 1 and 2. Camera Car 2 was stopped just in front of his position. Camera Car 1, just ahead of Camera Car 2, can be seen just beginning to pull away from where it had stopped 15 seconds earlier.
So, in fact, McLain’s motorcycle and Camera Car 3 were not constantly moving as Thomas assumed. The filmed record proves that Camera Cars 1, 2 and 3 had all stopped in front of the Texas School Book Depository for a period of about 15 seconds immediately after the fatal head shot, effectively refuting Thomas’ allegation.
Thomas’ Analysis of the Motorcyclist Seen in the Dorman Film
The Elsie Dorman film shows a motorcycle officer arriving at the HSCA’s first and second shot positions well after the fatal head shot. If the motorcycle officer seen in Dorman is McLain, as critics of the acoustic evidence contend and this analysis demonstrates, the acoustic evidence would be invalid.
Early supporters of the acoustic findings believed the Dorman film depicted McLain – identified by note papers that are visible clipped to the inside lower-left corner of his windshield – arriving at the positions dictated by acoustic shots one and two; until it was realized that the film was exposed well after the head shot. Acoustic supporters, like Thomas, have struggled to explain away the Dorman film ever since.
In his initial analysis, Thomas claimed that the motorcyclist seen in the Dorman film was actually officer Clyde Haygood. Thomas based his conclusion on an examination of a film made by Malcolm Couch. The Couch film shows Officer Haygood moving down Elm Street behind H.B. McLain and J.W. Courson. According to Thomas’ calculations, the Couch film corresponds to the moments immediately following those depicted in the Dorman film;  hence, the motorcyclist in Dorman is Haygood, not McLain. 
Thomas subsequently claimed that the officer seen in the Dorman film was Haygood’s escort partner, J.W. Courson.
To support this interpretation of the Dorman and Couch films, Thomas turned to the testimony of McLain and Courson. Thomas charged that McLain changed his initial testimony to the HSCA after he learned that his testimony supported the acoustic evidence. According to Thomas, McLain’s new version of events had him stopping on Houston Street, looking through the holes in the reflecting pool wall, and seeing Mrs. Kennedy climb out onto the trunk of the presidential limousine.
Thomas wrote, “However, McLain’s memory is contradicted by the recollections of J.W. Courson. Perhaps unaware of McLain’s statements, Courson related to researcher Larry Sneed in [his book] No More Silence, that just as he turned the corner on to Elm Street he saw Mrs. Kennedy out on the trunk of the President’s limousine. This event is seen in the Zapruder film about 2-4 sec after the head shot. Thus, Courson must have reached the corner at about the time of the head shot, and because McLain is well ahead of Courson in the Couch film, he must also have been on Elm Street at that time, as projected.” 
In short, Thomas embraced Courson’s account because Courson hadn’t change his story, and thus, was more reliable. But is he?
Testimony of McLain and Courson
A review of the entire testimonial record for McLain and Courson shows the accounts of both men to be problematic and, in particular, that Thomas was less than candid about the supportive nature of Courson’s testimony than he led readers to believe.
To begin, H.B. McLain was interviewed four times over 18 years.
On September 26, 1977, during the very first interview that McLain gave to HSCA investigators – before testifying in public – McLain said that he was just completing his turn from Main onto Houston Streets when “he heard what he believes were two shots. He looked up towards the Texas School Book Depository (TSBD) and saw pigeons fly from the roof of the Depository. An order came over his motorcycle radio to proceed to Parkland Hospital.” 
Curiously, McLain described his position at the time of the first shot exactly as was recorded in the Hughes film and that he heard the order from Chief Curry come over his own radio. The fact that this was McLain’s initial statement following the original event 14 years earlier, and before he had listened to the Dallas police recordings or seen any photographs, should not be overlooked.
On December 29, 1978, McLain testified publicly before the HSCA that he heard only one shot when he was on Houston Street, approximately halfway between Main and Elm.  McLain further testified that at the sound of the shot he looked ahead and saw pigeons fly out from behind the Book Depository. After turning onto Elm Street, McLain heard Chief Curry say, “Head for Parkland
Hospital.”  McLain couldn’t recall which channel his radio was set to that day. Gary Cornwell, deputy chief counsel, asked McLain, “Then it would be fair to state that since you neither have a distinct memory nor, in fact, recall using your radio, we simply can’t determine from your memory which of the two channels your radio may have been on at the time of the motorcade; correct?” McLain replied, “No, sir.” 
What Cornwell failed to note is that if McLain heard Curry instruct officers to go to the hospital, he must have been listening to channel two – which the entire motorcade was tuned to that day. Doesn’t McLain’s recollection of the statements he heard that day constitute his “memory” of what channel his radio was tuned to? Not necessarily, according to the HSCA and acoustic evidence supporters.
Under questioning, McLain told HSCA deputy chief counsel Gary Cornwell that if an adjacent motorcycle was close enough to his own, it would be possible for him to hear instructions coming over the adjacent motorcycle’s radio. Unfortunately, McLain was not asked if it was probable that he heard Curry’s instructions coming from another radio on the day in question. While supporters of the acoustic evidence are quick to accept the explanation for McLain’s ability to hear Chief Curry’s instructions on Channel Two and still have his own microphone stuck open on Channel One, it requires one to also accept one of two improbable circumstances: One, that McLain’s radio was tuned to the wrong channel (Channel One) for the entire thirty-nine minutes before the shooting and didn’t realize he could not hear the instructions being given by Chief Curry coming from his own radio; or two, that McLain inexplicably switched to Channel One at periodic points throughout the
motorcade,  the last time being two minutes before the shooting.
It also raises the question as to why the instructions McLain supposedly heard from a nearby radio were not recorded on Channel One as crosstalk. After all, the radio microphone was designed to pick up the sound of human voices over the sound of the motorcycle engine, and we know (even by Thomas’ assessment) that the motorcycle with the open microphone was running slow enough during the period in question to allow any nearby radio to be audible. Why didn’t the police recording capture the sound of the radio McLain supposedly heard?
But much more important than these two common sense arguments is the fact that the filmed evidence proves beyond question that no motorcycles were anywhere near McLain before, during, or after the shooting, and therefore, McLain couldn’t have heard Chief Curry’s instructions coming from anywhere but his own radio.
For instance, the Hughes film shows McLain’s escort partner, Marion L. Baker, to be 45 feet away and slightly ahead of him as they turn from Main onto Houston Streets. Considering the crowd noise and the string of motorcade vehicles between them, it would appear highly unlikely that McLain could have heard Baker’s radio at that distance. And yet, Baker is the only motorcycle officer close to McLain. Furthermore, the films and photographs that cover the seconds that follow the shooting don’t show McLain in proximity to any other motorcycles from which he could have heard Curry’s instructions.
In 1979, after the HSCA’s final report was published, McLain told former radio dispatch supervisor James C. Bowles that he was on Houston Street in the middle of the block when he heard one shot and saw pigeons fly up from the TSBD. He was stopping or had stopped at the time. “I don’t recall ever hearing the other shots – just one which I guess was the first.” He looked through an opening in the decorative wall on the west side of Houston Street and saw Secret Service Agent Clint Hill running behind the presidential limousine and jumping onto the rear of it. Then Chief Curry radioed for everyone to go to Parkland Hospital. McLain turned on his siren. As he turned onto Elm Street, he saw Bobby Hargis trying to straighten up his motorcycle. By the time he reached him, Hargis was running up the grassy knoll. McLain then accelerated out of the plaza. McLain reiterated that he “never left Houston Street until after the chief said for us to go to the hospital and for someone to check the overpass.” McLain added, “Had the committee [HSCA] staff told me what they had in mind it would have made a difference in my testimony. There were at least deceitful if not outright dishonest with me.” 
Finally, in an interview conducted between 1987-95 with author Larry Sneed, McLain stated that after turning from Main onto Houston he caught up with the motorcade cars in front of him and stopped right by the side entrance to the old jail about midway between Main and Elm Streets on Houston. “I heard one very clear shot,” which seemed to come from directly ahead of him. He looked up and saw pigeons fly from the roof of the TSBD. “I could see the limousine off to my left on Elm and saw Mrs. Kennedy crawling on the back of the car…About that time the chief came on the radio and said, ‘Get to Parkland Hospital!’ …” As he sped down Elm Street, he noticed Bobby Hargis crawling on his hands and knees across the grassy knoll. McLain caught up with the limousine on Stemmons somewhere around the Continental overpass. Upon listening to the recordings in 1979, McLain declared that the open microphone was clearly mounted on a three-wheel motorcycle, not a two-wheel motorcycle like the motorcade escorts rode. The three-wheeler makes a distinctive sound. 
Obviously, McLain’s account of the events of November 22, 1963, has changed over time, which is typical of eyewitness accounts. While Thomas was quick to dismiss McLain’s testimony because of the changes he offered over time, Thomas failed to be as critical of Courson’s account, which is at the very least equally contradictory.
J.W. Courson was interviewed three times over the course of 16 years. During his first interview of record in 1979, Courson told J.C. Bowles that he had just turned off of Main onto Houston and stopped just north of Main Street and waited for the White House Press bus (Motorcade Vehicle No.17) to complete its turn onto Houston Street when he heard three shots that “definitely came from ahead of me…” He looked to the west toward Elm Street and the direction of where the president’s limousine should have been but couldn’t see anything. Courson then took off from his position on Houston Street, passed numerous motorcade vehicles, and turned onto Elm Street. He saw an officer, Bobby Hargis, on his hands and knees. The lead vehicles had already cleared the Triple Underpass. Courson sped up and caught them on the access road to the freeway. He stayed with the presidential limousine all the way to Parkland Hospital. 
In this early account, Courson reported that he didn’t “see anything” when he looked toward the president’s car after the shooting, a point that conflicts with the later account accepted by Thomas.
During a second interview in 1986, Courson stated that he was two cars in front of the White House Press Bus, which places him near the fifteenth vehicle in the motorcade – Congressman’s Car No.3. – approximately 100 to 120 feet behind McLain. Courson indicated that he was on Houston; 60 feet from the Elm and Houston intersection. He heard three shots. He turned onto Elm Street and saw Secret Service agent Clint Hill jump onto the back of the limousine to assist Mrs. Kennedy who was on the back of the limousine. Courson stated that he and McLain moved down toward the limousine and got on either side of the rear of the limousine – Courson on the left; McLain on the right. Courson stated that he caught up with the limousine before they reached the Triple Underpass. 
In this second retelling, Courson included two impossibilities in his account. First, he stated that he saw Secret Service agent Clint Hill jump onto the back of the limousine just as he arrived at the Elm & Houston corner. Yet, the Dorman film shows the motorcyclist that Thomas contends is Courson arriving at the intersection well after Hill had jumped onboard the limousine. Second, Courson claims that he and McLain caught up with the presidential limousine before they reached the Triple Underpass. Again, the Couch film proves that the limousine had cleared the Triple Underpass long before Courson had traveled half the length of Elm Street.
In a third interview conducted between 1987-95 with author Larry Sneed, Courson stated that after turning from Main onto Houston he had to stop “due to the limousine having to make a sharp left turn ahead on Elm which slowed the motorcade.” While stopped, Courson heard three distinct shots coming from a single location although he couldn’t tell exactly where because of the echo pattern. The first two shots were closer together than the second and third shots. Courson tried to look to his left down into the plaza but couldn’t see anything, then sped ahead to catch up with the president’s car. As Courson rounded the corner at Elm and Houston, he could see that the limousine had stopped and Mrs. Kennedy was on the back. A Secret Service agent helped her back into the car and the limousine took off. Courson caught up with them as they entered the Stemmons Freeway ramp. 
It is this third retelling that Thomas embraces as truth, yet, it too has an insurmountable amount of problems. First, Courson states that he stopped on Houston just north of Main “due to the limousine having to make a sharp left turn ahead on Elm which slowed the motorcade.” Yet, the Hughes film shows that the limousine had already turned onto Elm before McLain (who was 100 to 120 feet ahead of Courson) had even reached the Main and Houston crosswalk. Consequently, Courson must have been still on Main Street, approaching Dealey Plaza, when the presidential limousine made its turn onto Elm. Second, Courson recalled hearing three shots from a single location; not the five shot scenario from two or more locations advocated by Thomas. Third, Courson stated that after the three shots he looked down into the plaza, couldn’t see anything, and then sped ahead to the Elm and Houston corner from where he could see that the presidential limousine had stopped, and a Secret Service Agent was assisting Mrs. Kennedy back into the car. Of course, the limousine never stopped on Elm Street, as the Zapruder film proves.
What’s important to note is the conflict in the timing of the sequence Courson proposes versus the one advocated by Thomas.
You’ll recall that the Dorman film shows the motorcyclist (identified by Thomas as Courson) slowly approaching the Elm and Houston intersection just 2.95 seconds after the fatal head shot. How could Courson’s account possibly be true if he is indeed the officer in the Dorman film, as Thomas asserts? Courson claimed he was stopped on Houston 180 feet from the Elm and Houston intersection when he heard three shots. A short period of time elapsed, as Courson looked down into the plaza. Unable to see anything, he then – and only then – accelerated across the 180-foot distance to reach Elm and Houston. How could all of that have happened in 2.95 seconds?
The filmed record shows both McLain and Courson’s accounts to be inaccurate, which is not surprising given the passage of time. Eyewitness accounts are notoriously incomplete and contradictory. That is why the filmed record and scientific evidence outweigh human recollection.
Allegations that the Photographic Record is Ambiguous
In 2001, Thomas concluded, “The bottom line is that the film evidence is not definitive with regard to whether McLain was or was not in exactly the right positions required by the acoustical evidence because we simply do not have pictures showing these positions when McLain is predicted to be there. However, if McLain was in continuous motion between where the motion pictures by Hughes and Couch show him to be, he would have been at least close to the predicted positions...” 
Thomas’ insistence that the photographic record is too ambiguous to answer the question as to whether McLain was in the right location at the right time to transmit the impulse sounds thought to be shots is false and misleading.
The Kennedy assassination is arguably the most photographed murder in history. There is an abundance of films and photographs available to determine the truth in a definitive manner, assuming of course that someone has the time and inclination to do so.
The HSCA failed to explore the photographic record adequately enough to answer the question largely because they ran out of money and time to do so. Thomas, and other supporters of the acoustic evidence, have had the resources available to them to answer the question of McLain’s position at the time of the shots but have failed to do so for reasons only they know.
The epipolar geometric analysis presented herein, makes it abundantly clear that the record is not ambiguous, as Thomas contended. As expected, the nine amateur films that captured the presidential motorcade’s journey through Dealey Plaza synchronize in only one way and that synchronization proves conclusively and beyond any doubt that no police motorcycles – including Officer H.B. McLain’s – were anywhere near the locations predicted by the HSCA’s acoustic experts, and consequently, the committee’s acoustic evidence of a conspiracy in the Kennedy assassination is invalid.
Published by Oak Cliff Press, Inc., P.O. Box 608, Milford, MI 48381-0608