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FORENSICS 144: BUMPER TAG

August 19th, 2011

This essay might be of special interest to writers of detective and mystery stories who would like to enrich their stories by providing their readers with a gift of some extra details. It might also be of general interest to many other readers.

Unfortunately, the tag referred to in the title is often one affixed to the toe of a dead body.

Until one early Sunday morning in July, Marion, 42, had never met Lamar, 16. Marion had just finished her night shift as a Chicago 911 police dispatcher and was driving home. Lamar had allegedly left a party where he had drunk vodka, smoked marijuana and taken ecstasy. He noticed a man paying for parking while leaving the engine of his Range Rover running, and he allegedly hopped into the vehicle and sped away.

According to police, Lamar had been stopped for having run a red light. When the police tried to question him, he suddenly backed the Range Rover, nearly striking two officers and ramming a squad car in the process. He than took off with police in vigorous pursuit. After having led the police chase for about a mile, Lamar ran through a stop sign. It was here that at least the vehicle driven by Lamar met that driven by Marion for the first and last time. The meeting smashed Marion’s vehicle and sent it spinning into a fire hydrant, causing Marion’s eventual death.

Lamar had not finished creating a swath of destruction. He sped off once more and rammed a parked car with such force that it left the car, off the ground, imbedded sideways in a brick wall. He then abandoned the Range Rover and fled on foot, but he was soon apprehended.

Lamar was subsequently charged as an adult with murder and lesser crimes and held under a $1 million bond. He had previously been sentenced as a juvenile to probation for having twice been found in possession of stolen vehicles. Surprisingly, Lamar was an honors student who excelled in two sports at a high-quality school that prepares boys for success in college.

Another sad incident occurred when police tried unsuccessfully to stop the driver of a Dodge Neon for having violated a traffic rule. While fleeing, the driver of the Neon, which turned out to have been car jacked, ran a stop sign and collided with a GMC Sierra pickup truck. Five children were in the truck. Four of them were killed when ejected by the crash, and the fifth died later at a hospital. Their two parents were hospitalized in serious condition. Three adults riding in the Neon were also killed in the collision.

Reportedly, 85 percent of the more than 100,000 high-speed police chases in the U.S. every year involve nonviolent offenders. According to federal statistics, the number of persons killed every year during police chases hovers about 350. About a third of those are innocent bystanders. The numbers reflect only those deaths that are reported. The reporting of such deaths is not mandatory, however; and the actual number is thought to be much higher, perhaps by a factor of three or four. An academic expert in such matters estimates that from 35 to 40 percent of police chases end in crashes.

Many police forces have tried to reduce the number of tragedies by issuing rules governing when to chase and when not to chase. Risking lives by chasing someone who has committed a minor traffic infraction and simply panicked is not worthwhile, but a police officer usually has no way of knowing whether the driver is guilty of a minor traffic infraction or is a viscous serial killer. Reducing the number of fatalities, injuries and costly lawsuits to zero is probably impossible, but there is a recently developed technology that should result in a significant reduction.

John and his partner, Frank, were driving in a northerly direction in their police cruiser and had turned left behind a west-bound Ford Mustang. As they were beginning the turn, John had noticed a startled expression on the face of the Mustang’s driver when he recognized the cruiser. John had seen such an expression many times during his long career as a policeman, and it usually indicated that the driver was up to no good. He trailed the Mustang as Frank called in its license number. The number was reported to be that of a stolen car, and John activated the cruiser’s siren and flashing lights. The Mustang’s driver responded by accelerated away from the cruiser.

John closed the gap between the two cars, but traffic made forcing the Mustang to stop dangerous. Frank manipulated a few controls and John slowed the cruiser, allowing the Mustang to pull away. Thinking the police had abandoned the chase, the Mustang’s driver slowed. A few minutes later, he found himself boxed in by police cruisers. Having no viable alternatives, he surrendered with no further resistance.

The controls that Frank manipulated were those of a StarChase Pursuit Management System, which targeted the Mustang by aiming a laser at it . Mounted on the front of the police cruiser was a launcher that used compressed air to fire a tracking projectile at the Mustang after it had been targeted. The projectile comprised a global position system (GPS), a radio transmitter and a power supply. These components were embedded within a strongly adhesive compound that adhered the projectile to the Mustang.

The GPS transmitted the position coordinates of the Mustang to a dispatcher. The dispatcher was then able to track the Mustang on a digital roadmap such as depicted on television programs such as NCIS and direct other cruisers to a location where they intercepted the Mustang.

Thanks to the tracking technology, the stolen car was recovered; and there were no resulting injuries, fatalities or lawsuits.

ADDITIONAL INFORMATION:

Data from a StarChase Pursuit Management System can be downloaded and stored and is reportedly considered admissible evidence in court.

Very basically, GPS is a system that uses a mathematical analysis of the times it takes signals from a number of satellites to reach a GPS receiver to determine distances to the satellites and, from that information, the location and speed of the receiver. The signals include the time a signal is sent and precise orbital information. The accuracy of a position determination is proportional to the number of satellites engaged. Signals from three satellites provide a rough position. Signals from four provides more accuracy and can also be used to determine altitude if, for example, the GPS receiver is located in an aircraft. The system typically uses signals from four or more satellites simultaneously.

There are, of course, many military GPS applications such as precision weapon guidance, downed-pilot locating and patrol tracking. GPS satellites also house a variety of radiation sensors, and they actually represent a major portion of the U.S. Nuclear Detonation Detection System.

GPS time is based upon that of atomic clocks and is reportedly accurate to about 14 nanoseconds (14 billionths of a second). How does that compare with the accuracy of your watch?

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  1. August 19th, 2011 at 08:41 | #1

    Hmmm. If one uses a “watch” that receives a signal from an atomic clock, I suppose the 14 ns factor gets skewed a little by the length of the communication delay. You just can’t get quality tech these days. :-) But you do get quality from one Robert “Amalgam” Jones. Fascinating stuff, as always, Amalgam. And I’m blown away by the StartChaser system. Love that stuff. Hope SC goes into wide usage and proves practical in the field (or on the road). I’m starting to think that maybe you should investigate something else. What about crime fiction as a market? You have that chilling objectivity when you write as you do here, and that’s appropriate to everything from IN COLD BLOOD to Hannibal Lecter. I’d read anything you wrote in that vein, sir, and count myself greatly entertained and informed. Write on…

  2. Robert Jones
    August 20th, 2011 at 16:31 | #2

    You’re as accurate as always amigo. There is indeed a length of community delay. It has its own importance in that it is this very delay from each of a number of satellites that reveals their distances to the GPS receiver. A bit of trilateration (often referred to as triangulation) provides the location of the receiver.

    Amalgam

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