HAVING BECOME MULTIDISCIPLINARY, FIRE INVESTIGATION TODAY REACHES OUT TO AREAS OF EXPERTISE UNAVAILABLE TO FIRE INVESTIGATORS IN THE PAST.
BY CHARLES G. KING AND JAMES I. EBERT, Ph.D.
Fire investigation involves tediously putting together bits and scraps of burned and unburned material found at a fire scene to reconstruct as closely as possible the original condition of a room, a house, a barn, a boat, a plane, or any other structure or vehicle.
Methodologies used to investigate a fire include drawing schematics, layering debris, photographing, sifting, vertical and horizontal excavations, and reconstructing small and large artifacts that exemplify how people negotiate the day-to-day challenges of human life.
What fire investigators do may be termed “real-time archaeology.” The fire investigator’s “pit” is the fire scene. Fire investigators, however, have the unique advantage of living in the society they investigate. In viewing and exploring the remains of a fire, the investigator knows generally where everything goes and how it is used. In most instances, he can reconstruct a room from fire debris. In some cases, the job is made easier because prefire photographs and videotapes are available.
The investigator can go from the area that suffered the least burn damage to that with the greatest burn damage, trying to locate and identify the area with the lowest point of burning, which usually is the fire’s origin.
We like to call any fire that can be investigated in this manner a “pure archaeological dig.” We have worked as a team (King as the origin and cause investigator; Dr. Ebert with his expertise in photogrammetry and site reconstruction) on a number of forensic cases involving fire. Photogrammetry is the art and science of obtaining reliable information about physical objects and the environment through the processes of recording, measuring, and interpreting photographic and other types of images. Modern archaeology is so complex that many projected excavations now require multidisciplinary teams of archaeologists, botanists, geologists, zoologists, photogrammetrists, and other specialists who work together on closely integrated research problems, such as the origins of food production.
 |
(1) The stove is to the left of the microwave. The cabinets and the microwave oven are in the corner. The shelf over the microwave oven did not burn or collapse. The microwave oven was under the corner of the kitchen where the cabinets met. (Photos 1-5 courtesy of Charles G. King Associates, Inc.; photos 6-11 courtesy of Ebert & Associates Inc.) (2) The shelf over the microwave oven is relatively unburned; the counter beneath it is intact. (3) The paneling behind the microwave oven is clean, indicating that the microwave protected the wall instead of burning it. (4) The fluorescent light fixture collapsed between the wall studs, over the “V” pattern over the sink.
In fire analysis, however, most of the time the only “expert” at the scene is the investigator, and the only object of analysis is the fire. Criminal and civil litigation cases sometimes require interdisciplinary study; depending on the fire incident, those involved might include an origin and cause expert, a forensic pathologist, an engineer, a forensic odontologist, a photogrammetrist, a product expert, a warnings expert, a human factors expert, and so on.
Fire investigators do not have to choose a site as archaeologists do. Crimes, accidents, or “acts of God” indicate the site. Investigators know exactly what to look for in every instance: first, the origin of the fire and, second, the cause of the fire.
Following is a case history that illustrates the team approach that incorporates the fire investigation and archaeological/photogrammetric skills approach.
FATAL KITCHEN FIRE
One particularly tragic product liability case on which we worked involved the death of a young child. As emotions always run high when somebody-particularly a child-dies in a fire, it was imperative that we reconstruct the area of the fire’s origin in a manner that was accurate and easy for a jury to understand.
Although the fire was electrical in origin, the homeowner’s fire expert mistakenly concluded that the cause was a defect in a microwave oven in the kitchen. The fire investigator’s job was to locate the origin of the fire. The photogrammetrist’s responsibility was to visually translate the often indecipherable debris at a fire scene into line, depth, shade, and shadow that could be comprehended even by individuals who were not expert fire investigators.
The kitchen, all sides agreed, was the area of the fire’s origin. It consisted of a refrigerator and a stove set at a right angle to a kitchen counter. The counter abutted the wall to the right of the stove. The kitchen sink was set into the counter, and the counter made a turn a few feet past the sink to enclose the area in a wide “U” shape. Kitchen cabinets were over the refrigerator, stove, and all of the countertops. The microwave oven, said to have caused the fire, was kitty-corner on the counter, to the right of the stove, under the right angle at which two cabinets met.
Given the overall destruction, burning, charring, and collapse of much of the material in the kitchen, it was immediately obvious to us that the underside of the cabinets directly over the microwave oven, as well as the rear paneling behind the microwave oven, exhibited very little fire damage relative to the rest of the room. Although there was some charring, the cabinet doors had not burned off, the shelves had not collapsed, and the wall behind the lowest shelf inside the cabinet-the one closest to the microwave oven-still retained the original color of the paint. Significantly, the countertop beneath the microwave oven was also unburned.
Analysis of the microwave oven itself showed that all of the fire damage was external and that its electrical components could be excluded as a cause of the fire. All of these findings led us to look elsewhere.
Based on the heavy burning in the area over the sink, which was the only place in the kitchen where the fire had been so intense that it burned through the wall to the room behind it, we decided to look there. It was there that we found the fire’s origin. No cabinets were directly over the sink. Instead, at the height of the top of the cabinets, behind a narrow decorative panel, was a fluorescent light fixture, which the homeowner had installed. Although he was not a licensed electrician, he had done all of the wiring in the house himself. The wiring to this fixture was run inside the wall, between the studs. The fluorescent light fixture collapsed between the wall studs. There was a classic “V” pattern in the wall over the kitchen sink. Burn patterns on the shared wall of the room behind the sink, where the fire had burned clear through to the bathroom on the other side, revealed the same heavy charring and “V” pattern. Close examination of the wiring revealed multiple arcs on the wires, which clearly indicated that short-circuiting had occurred.
The studs on either side of the short-circuited wires were heavily charred. Following the wires back to the circuit breaker, which had tripped, we could trace the progression of the fire from the beaded wires, as the ignition source, to the rest of the burn damage throughout the house. There was no question that we had found the fire’s origin. The “V” pattern over the sink pointed the way.
 (7) A three-dimensional model of the involved area of the kitchen. |
Nor was there any question about the cause. An electrical engineer was brought in to review the evidence. It was his opinion also that the cause of the fire was electrical and that it had originated in the shorted electrical wires in the wall.
At this point, Dr. Ebert was brought into the case.
On the one hand, we had an extremely sympathetic victim whose child had died in a fire. The fire had occurred around the holidays. We would show the jury the videotape used to aid us in visually reconstructing the kitchen. The child who died could be seen in the video, exacerbating in the minds of all who saw it the tragedy of the death.
Since the homeowner had installed the electrical wiring in the house, he could not accept the possibility that his workmanship might be the cause of the fire. This may explain why he and his family viewed the microwave oven as the ignition source. From their point of view, it had to be.
It became vitally important that we, who knew that the microwave oven had not started the fire, present a clean, clear, and lucid defense. Critical to that defense were the exact location of the microwave oven on the counter under the cabinets and the precise relationship of the microwave relative to the rest of the kitchen.
This was where the expertise of Dr. Ebert came into play.
THE PHOTOGRAMMETRIST’S POINT OF VIEW
Photographs are one of the first types of information collected at most crime or accident scenes and hopefully (but not always) can be taken before the positions of the items have been physically disturbed. They record a spectrum of valuable information that is at least partially independent of the investigator and photographer, although they do not invariably show “everything.” Nor do photographs necessarily and automatically depict the “truth.” Officials or experts at crime, accident, or fire scenes also often draw schematics and write reports of their observations and conclusions, the results of which vary widely in terms of detail and sophistication.
Schematics and on-scene notes are filtered through the investigator’s feelings and psyche, which may be difficult to interpret in the middle of the night in a rainstorm at a murder scene. Therefore, once a burned building has been razed or a body has been removed and buried, photographs usually provide the most unbiased evidence-and the evidence most open to reinterpretation.
When investigators comb through the area of a contemporary fire scene looking for evidence, they move things around. They sweep ash off a burned portion of floor or move an appliance suspected of having started a fire several feet or even several rooms away from its original position. Fortunately, in some cases, these investigators take photographs of the fire scene and the objects at the fire scene as they are doing so.
Often, they take lots of photographs. It seems to be an unwritten rule that at a fire and many other types of investigations, each of the experts inspecting the scene takes a minimum of three rolls of film or about 100 photos apiece. If a fire is suspected of being arson, the fire department investigators, of course, take their sets of pictures. If the fire is deemed to have been accidental, and if the fire department or insurance investigator points to an appliance as the cause of the fire, then one or another form of litigation may be initiated, and plaintiffs’ experts are called in to conduct the next level of investigation. Once they determine which appliance they think “did it,” the manufacturer, which is now the defendant in a lawsuit, brings in its own experts.
IMAGE-PROCESSING TECHNIQUES
In some cases, there may be as many as 500 or 600 photographs of a fire scene. Because the residue of a fire is so difficult to photograph, it’s difficult at first to see what the photographs reveal. Often, there’s no electricity after a fire, so the area is dark. In determining what an object is, we rely on its color as much as its shape, but because everything that has been burned has lost its color and is about three shades of gray, black, and brown, it’s also difficult to make out individual items.
Therefore, image-processing techniques are used to make what’s in the photo as clear as possible. Before computer or digital methods became available in the mid-1980s, the image-processing system involved focusing a high-quality video camera on a photo that had been mounted on a light table. This system employed analog circuitry to improve the images’ contrast and brightness, performed “edge enhancement” to help counteract fuzziness in the pictures, and enlarged small details so that they could better be seen. The digital methods do all this as well as digital mapping.
The photos of the kitchen fire scene discussed above were processed digitally. Very few photographs actually have an optimal distribution of the light-to-darkness values that make them up. This was certainly true of the photo of the kitchen where the fire occurred.
As is often the case, no negative was available, so the photo print was scanned to create a digital file in which the image is represented by a matrix of squares, which are picture elements or, as imaging scientists call them, pixels. Each pixel has a digital value from 0 (black) to 255 (white), which indicates its brightness relative to the other pixels in the image. In the image originally scanned from the dark photo print of the kitchen, the distribution of pixel brightness values was clustered around the low end of its range. Histogram stretching was applied to increase the spread of values in the image. Details in the resulting photo were much easier to see.
 |
The photo is still very confusing, however, largely because of the jumble of burned, fallen, and misplaced objects. At the homeowners’ deposition, we were given a videotape of the interior of the house taken by a family member before the fire.
The view of the kitchen that appeared in that video was almost at the same angle as the one in the enhanced photograph. As the camera panned around, those video frames were made into a composite.
But exactly what did that composite show? A three-dimensional map or model of the cabinets, counter, appliances, and other room details were created to illustrate the locations of objects in the kitchen prior to the fire.
By comparing the three-dimensional model with the postfire scene photo and the prefire video, the configuration of the other items around the microwave oven-which was suspected of having started the fire-is quite clear. The microwave had been placed in the corner of the counter, at a 45° angle to each of the walls behind it. The cabinets above the oven also met in a right angle, just above it. A coffeemaker and a roll of paper towels on a holder attached to the underside of the upper cabinet were between the microwave oven and the sink.
Our purpose in creating these composites and models and in enhancing the photographs of the fire scene was to provide to a potential jury clear, recognizable, and accurate representations of what the kitchen looked like before and after the fire so that the jurors could better understand the sequence of events. Close-up photographs of the corner in which the microwave oven was located were also image-processed for clarity. One shows the corner area with the oven still in place; the other shows it after the microwave had been removed.
The cabinets above the oven were relatively undamaged (compared with the cabinet to the right of the sink). After the oven was removed, we could see that the counter beneath and the walls behind it were also unburned. Interestingly, the wall to the right of the microwave oven, behind the paper towel dispenser, was completely untouched by the fire. This is significant, since both were so close to the microwave oven.
As we moved farther away from the microwave oven and the paper towel holder, however, the burn damage became more intense. The wall over the sink, as well as the bathroom side of the wall behind it, was consumed by the fire in a classic “V” pattern.
The extension of this model, which was also taken from scene photos, showed the kitchen and details of the 2 2 4 studs in the room above the kitchen, which exhibited the extension of the “V” pattern on the upstairs bathroom wall.
PUTTING IT ALL TOGETHER
Combining our technical expertise, we were able to establish that the microwave oven did not cause the fire, that the area in which it had been located was relatively undamaged by fire, and that the fire originated in the wall where a fluorescent light fixture had been located.
Unquestionably, the cause of the fire was electrical in nature; the microwave oven was exculpated.
Because photographs of the fire scene were made available to us and because we acquired a prefire videotape of the kitchen, we were able to combine sophisticated photogrammetric techniques with good old-fashioned fire analysis.
Having become multidisciplinary, fire investigation today reaches out to areas of expertise unavailable to us in the past. We work together and learn from each other. As always, our goal is to determine how a fire scene looked before a fire, what happened, how it happened, and why it happened.
Copyright © 2001, Charles G. King, James I. Ebert, Ph.D.
CHARLES G. KING heads Charles G. King Associates, Inc., a fire and arson investigation firm he founded in 1980. Previously, he served 23 years in the Fire Department of New York, where he was a firefighter, a fire marshal, and a supervising fire marshal of a technically sophisticated surveillance unit. He was a special agent assigned to investigate organized crime and corruption at the New Jersey State Commission of Investigation for more than two years. His articles on fire/arson investigation have been published in fire service/arson investigation publications. He wrote the chapter on arson investigation for The Fire Chief’s Handbook, Fifth Edition (Fire Engineering Books, 1995).
JAMES I. EBERT, Ph.D., is chief scientist at Ebert & Associates, Inc., an Albuquerque, New Mexico, firm specializing in forensic, environmental, and archaeological applications of photogrammetry and digital imaging and mapping technologies. He is a certified photogrammetrist and a fellow of the American Academy of Forensic Sciences, a member of the New York State Police Medicolegal Investigations Unit, and the director of digital mapping and data collection for Rutgers University’s Olduvai Landscape Palaeoanthropology Project, which undertakes research into ancient hominids and their behavior at Olduvai Gorge in Tanzania.
