it was supposed to be a routine motorcade for the queen of england, but along this two-lane highway leading to yosemite national park, a car carrying secret service agents collided with another, killing three people. what went wrong? who was responsible? hidden in this photograph was the clue to the mystery. in 1983, yosemite national park in california was selected to be the site of a royal visit by the heads of the british monarchy. queen elizabeth ii and prince philip were scheduled to tour the park following a visit with president reagan at his california home. don schneider, a photographer and reporter for a local radio station, monitored the preparations for her arrival on his shortwave radio. >> in advance of that, there were three carloads of secret service agents that were going to yosemite to provide security at that location for her. they were not directly involved in her transport, but were supposed to be preceding her and have things ready up there in the park. >> three cars carrying secret service agents traveled along highway 132, a two-lane road that snaked its way through the foothills of the sierra nevada. there were three agents in the second car. the driver was george labarge, 41 years old. he was married with a young son. >> george labarge was a 14-year veteran of the secret service from dayton, ohio. he had been, for many years, assigned to the protection detail of the vice presidents.

>> as the three agents made their way eastward towards yosemite, deputy sheriff rod sinclair of the mariposa county sheriff's office was preparing to check the road closings for the queen's visit. >> rod was a big man, heavy, and was quite macho and authoritative. >> we had heard, but we never deduced hard evidence of this fact, that sinclair was something of a loose cannon. >> sinclair and another deputy climbed into a chevy impala patrol car, similar to this one, and sped west on highway 132 to check on the road closings. at the same moment, the secret service agents continued eastward in a small rental car. none of the agents was wearing a seatbelt. the road was wet from a light rain. both sinclair and the convoy of secret service agents believe the road had been cleared of traffic. >> the sheriff's car was coming

from our right, around this curve. the secret service cars were coming from our left. >> the road curved around the small hill that blocked the driver's view of approaching cars. that location had been the scene of seven accidents in the previous three years. at 10:31 a.m. on march 5th, it happened again. the two cars entered the curve at the exact same moment. the three agents were killed instantly. protected by seatbelts, the two deputies suffered only minor injuries. it appeared to be a terrible but unavoidable tragedy. but was it? the answer lay in the scarred surface of the roadway and the twisted metal of the wrecked cars.

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a car with three secret service agents and a sheriff's patrol car with two deputies collided along a back road near yosemite national park.

the collision demolished both cars and claimed the lives of three secret service agents. the question facing investigators was why? within two hours, a special unit of the fresno, california, highway patrol called the multidisciplinary accident investigation team, or mait, arrived at the scene. >> their job is to take a look at everything that's there, document it, classify it, photograph it, and then use it later in the reconstruction process to develop a model as to how the vehicles were moving. >> the investigators found the point of impact marked by scattered debris, a pool of brake fluid, and more than a dozen gouge and scrape marks. they also found a set of skid marks 64 feet long. they began in sergeant sinclair's lane, crossed the yellow center line, and ended in the oncoming lane traveled by

the secret service. it was clear the skid marks would be a critical clue. the mait investigators then interviewed eyewitnesses, one of whom was driving behind the secret service cars. according to her, the agents did nothing wrong. >> they were relaxed, taking their time, driving along at a reasonable speed for the area and the terrain. >> after gathering all the evidence, the mait investigators began the hard work of reconstructing what caused the accident. >> what i'm doing here is called motion analysis. i'm using the scaled physical evidence and the scaled vehicles to try to determine how the vehicles were moving during particular phases of the collision. >> the motion analysis provided the data for a series of critical calculations. the first was the momentum of each car immediately after the collision.

momentum is determined by multiplying each car's speed by its weight. the investigators knew the weights of both cars. by measuring the distance and direction they had slid, their rotation, and the amount of friction, they were able to calculate their post-impact speeds. 30 miles per hour for the sheriff's car, 24 miles per hour for the secret service. next, they looked at the angle at which the two cars had collided. >> the angle of impact in this particular collision evaluation was critical to determining how this collision took place. >> mait calculated that the two cars collided at a ten-degree angle, almost directly head-on. they already knew the direction the sheriff was traveling from the skid marks, so the angle of impact allowed them to calculate the path of the secret service car. >> ten-degree approach angle between these two vehicles

places the secret service dodge aries within its lane of travel, and moving slightly from left to right as a potential evasive tactic as impact takes place. >> eyewitness testimony established that the secret service agents were driving at around 35 miles per hour. the critical question was how fast was deputy sinclair driving? sinclair claimed he was going 55 or 60 miles per hour. applying the laws of conservation of momentum, mait calculated he was actually doing 76 miles per hour. >> when he came into that curve, his vehicle was out of position for the speed that he was traveling. when he saw traffic coming at him in the eastbound direction, he simply didn't have enough distance or enough time to safely negotiate the curve. he panicked, locked up the brakes on the patrol car. once he did that, the patrol car slides straight across the

inside of the curve, into the opposing traffic lane and struck the second secret service vehicle. >> based on its three-week investigation, the california highway patrol believed that sergeant sinclair was grossly negligent and recommended that he be criminally prosecuted. >> i believe the facts were there, given the circumstances, that you could make a case for misdemeanor manslaughter. >> but one man had lingering doubts about the investigation. attorney charles brunn, who represented rod sinclair, believed something vital might have been missed. >> rod kept saying over and over again, they were in my lane of travel. they were heading right at me. there was nothing i could do but hit the brakes. >> was deputy sinclair telling the truth? rod hired his own investigators to find out and what they would discover would force the highway patrol to reopen their

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three secret service agents had been killed in a near head-on collision with a sheriff's patrol car. all the evidence indicated that deputy sheriff rod sinclair was solely to blame.

but then, a local photographer, don schneider, was looking at slides of the accident when he discovered a clue the highway patrol had missed, another skid mark. >> it was a surprise to me to see the mark there, because i had not observed the skid mark at the accident site. and i asked the question of the group that was there, hey fellas, what is this? and pointed to the skid mark that i saw on the screen. it was obvious in the matter of discussion a few moments later that this had something to do with the secret service car. >> attorney charles brunn showed the faint skid mark to a team of accident reconstruction experts. from the angle of the mark, it appeared that the secret service car had been over the center line and was turning back into its own lane when it was hit. >> and all of a sudden, i thought to myself, we have cause here for optimism.

sergeant sinclair, it would seem, was vindicated. he said they were coming right all the him. >> the new evidence suggested that sinclair had hit the brakes, not because he was going too fast, as the highway patrol contended, but because he saw danger ahead. the california highway patrol investigators dismissed the new evidence, calling it the phantom skid mark. >> the chp experts covered that ground on their hands and knees, literally inch by inch, and never saw that skid mark. >> why they didn't find it wasn't clear, but the discovery gave new impetus to brunn's team of forensic accident reconstruction experts. paul kayfetz, a photographer and engineer, is an expert in something called photogrammetry. >> it's a $6 word for making measurements from photographs -- or using photographs to make measurements. >> brunn's experts needed a map

of the accident scene with the skid marks to conduct their investigation. kayfetz's job was to reproduce the mark on the road in the exact position so a surveyor could map its location. he began by making a 35-milimeter negative of schneider's photograph showing the skid mark. >> i put it into a special camera that i take back to the scene. i locate the exact point from which he took his photograph, and looking through my camera, i can re-mark the position of the skid mark on the ground and have a surveyor record it. >> the chalk marks helped kayfetz verify that the mark was exactly as it appeared in the photo. once the new survey map was created, dr. william blythe, an expert in applied mechanics and accident reconstruction, was able to trace the path of the secret service car.

the results confirmed that sinclair's statement, that the secret service cars were over the center line. >> i think that the amount of the vehicle over the center line, as i recall, was something in the neighborhood of one-third or one-half of the vehicle. it wasn't fully in the oncoming lane. >> the highway patrol had determined that the collision was virtually head-on. blythe showed that the sheriff's car had struck at an angle, as if agent labarge had been turning back to the right to get back into his own lane. dr. blythe determined that the critical skid mark was made by one of the front tires on the agent's car. the critical question was, which front tire? the highway patrol experts, after first denying the existence of the skid mark, argued it was made by the left. if they were correct, it meant

the secret service could not have been over the center line. using photogrammetry, kayfetz was able to determine the width of the tire that made the skid mark and prove that it was, in fact, the right tire. >> as it happened, the right front tire on the wrecked labarge car was almost an inch narrower than the other three tires. it had been replaced probably by a spare tire at some point. and that particular tire mark matched only that narrower right front tire. >> proving the skid mark belonged to the secret service car was one of two critical issues facing dr. blythe. >> what was the sheriff reacting to when he applied his brakes? was he reacting to his perception that he was going too fast to make the corner, or was he reacting to some other danger that he saw? >> the highway patrol found

sinclair was going too fast. but dr. blythe ran his own test using a patrol car identical to the one sinclair was driving. >> the range for the sheriff's vehicle i found was between 62 and 66 miles an hour. >> at that speed, sergeant sinclair had no reason to hit his brakes because he could have comfortably negotiated the curve. that left only one explanation. >> we felt there was negligence on the part of the drivers of the first two cars in that entourage in that they crossed the center line. >> let's begin a test run. >> to help prove these findings, brunn asked paul kayfetz to conduct a visibility study like this one, re-creating what each driver saw an instant before the collision. the results would reveal another surprising piece of evidence.

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a high-speed collision. three secret service agents killed. california highway patrol investigators determined that sheriff's deputy rod sinclair was solely responsible. but then the discovery of a skid mark in this photograph suggested the secret service was

also at fault. the problem was proving it. to reconstruct the critical moments before deputy sinclair slammed on his brakes, attorney brunn asked paul kayfetz to conduct a visibility study. >> what we were trying to find out is, did that skid and ultimate loss of control start because he perceived that the oncoming lead car was in his lane. >> kayfetz mounted cameras in vehicles identical to those involved in the accident, positioning them to record each driver's point of view. then, based on the physical evidence and the calculations of dr. blythe, he reconstructed the events that preceded the fatal collision. >> from this viewpoint, you can actually see that the lead car is halfway over the center line and the labarge car in front of

this car is also a couple of feet over the center line. >> now comes the view from the fourth car driven by a key eyewitness, mona crocker, who told mait investigators she had seen the accident happen. >> she testified that at no time did she see any of the three secret service cars cross the center line. she also testified that she saw the accident occur. >> kayfetz's reenactment told a different story. >> so this is mona crocker's viewpoint. and what's important here is that, although the lead car ahead of her goes halfway over the center line, straddles the center line, from her viewpoint, that is never visible because it's around the curve and over the hill. >> crocker thought she could see the position of the cars. in fact, she could not.

from the beginning, the critical question in the case was always, why did deputy sinclair jam on his brakes? kayfetz's dramatic re-enactment answered the question. >> now, from sinclair's viewpoint, we can see that he sees the lead secret service car straddling the center line just a bit more than a second before he begins to skid in a straight line across the highway. >> the last view is that of agent labarge just before the fatal crash. based on kayfetz's powerful reenactment and the work of brunn's team of investigators, a judge ruled that the secret service agents were partially responsible for the accident. he also ruled that the united states should reimburse mariposa county 30% of a $4 million settlement that had been paid to

the families of the secret service agents killed in the accident. >> i felt good that the judge believed sergeant sinclair that the secret service agents had driven across the center line. i felt very good about that. >> the verdict was later overturned on a technicality, but brunn and his team of forensic experts had proven their case. >> it is phenomenal and it is amazing what they can put together and how they can reconstruct an accident and how they can make little small pieces of evidence tell a story. >> there's satisfaction when the pieces come together in a case like this and other similar cases. >> that was a very powerful presentation, and i recall having a lump in my throat when i watched it.

it was as if you were in the driver's seat watching your life come to an end in that split second. it was a very powerful videotape. in 1993, the amtrak railroad experienced the deadliest train crash in united states history. 47 passengers and crew were killed, 103 more were injured. the cause of the accident was unclear. the clues to this mystery were etched in twisted steel and buried in the mud of an alabama bayou waiting for investigators to find them. amtrak sunset limited is the country's only remaining transcontinental train.