Investigation at a Suspected Arson Scene

Investigation at a Suspected Arson Scene

This article is a condensation of an address given by the author to the Southwestern Arson Investigation Seminar, University of Oklahoma, November 1962—The Editors.

ARSON INVESTIGATORS must approach the fire scene in much the same manner as you would approach a jigsaw puzzle. All the pieces are there; you just have to fit them together. To start the jigsaw you pick up first a piece that is obviously a side or comer. To start a fire investigation, go to the scene of the fire which is the cornerstone of the puzzle.

Most states have statutes permitting and authorizing search and inspection of the involved premises where a fire has occurred, and court decisions have established the right of fire and police authorities to enter a burning structure not only to squelch the blaze, but to make such investigation under general police power. The conditions and circumstances found during and following the burning and extinguishment compose the subject matter of the investigation—the Body of the Crime—if a criminal offense occurred, to which all elements of evidence and proof will attach.

The careful study of the fire scene and what it may reveal is the key to successful fire investigation. Investigation of the accidental fire may serve as a basis for improved engineering and fire prevention practices, while that of the incendiary fire with subsequent prosecution is the most effective deterrent for arson.

Arson and the fire triangle

For many years there has been instruction concerning the importance of the fire triangle—that heat, fuel and oxygen are necessary to produce and maintain fire. These three factors and the analysis of their possible association and connection can provide an excellent plan for the fire investigator to bear in mind as he approaches the fire scene. The presence and amount of each such factor to have caused an involved burning must be considered by the investigator in determining the cause, point of origin and path of burning. The discovery of a removed scuttle cover, adjustment of windows and other sources of air in an unusual manner and similar findings may afford a basis for the investigator to arrive at a tentative opinion that special care has been taken by some person to assure an adequate supply of oxygen.

The presence of a supply of fuel not usually found in the structure, or of inordinate amounts of common fuels in questionable locations, may mark a fire as incendiary. To develop the heat factor of the triangle in relation to arson, debris in the vicinity of heating or electrical appliances must be carefully examined.

Points of origin

The point or points of origin of single or multiple burnings should be determined as early as possible in the investigation. The comparison of various burned spots with reference to deep or shallow “alligatoring” of charred surfaces should determine the relative intensity and rate of burning. It may also be a means of determining the relative amounts or qualities of suspected accelerants where inadequate amounts remain for immediate identification.

While it is most often the rule that separate and uncommunicated fires within a structure tend to establish an incendiary fire, we must bear in mind that there are exceptions to all rules. The open-minded investigator often finds that such separate fires may be the result of embers falling, the droppings of melted and burnt asphalt, or the scattering of fire by burning curtains, clothing and similar material. Furnishings removed by the frantic efforts of occupants prior to the arrival of the firemen are not always readily recalled and explained by innocent persons. This study to be fair and correct requires time, effort, patience and digging into the charred debris to develop the true facts. True conditions remaining after extinguishment may or may not show just what did happen. The investigator should know the cause before permitting himself to form an opinion, but when he has sufficient evidence to establish a definite opinion, he should avoid wasting valuable time and get along with other phases of investigation.

Establish the opportunity

In the majority of extensive burnings the occupants are away from the structure at the time of discovery. In such instances the investigator should, on finding suspicious conditions, seek to establish the exclusive opportunity of the departed occupants to have prepared and arranged the touch-off. To develop this opportunity requires investigation on the scene as well as gathering related information concerning the departure, destination and other evidence connecting the suspected person or persons with the crime. Time is important here and it is not to be wasted in prolonged work at the fire. However, on leaving the scene before the examination is completed, make sure that the premises are guarded not only until the return of the investigator, but until the investigation is completed.

Numerous instances find the suspected occupants present at the structure for prolonged periods prior to and at the time of discovery and extinguishment. Quite often such occupants come forth with explanations for the fire which may or may not be reasonable, but the physical aspects and conditions at the fire may provide conclusive means of contradicting or confirming them.

Intensive examination of the fire should be made where there are known domestic difficulties, desire and efforts to sell or otherwise dispose of property, excessive and/or recently purchased insurance, removal of portions of contents, and financial distress.

The possibilities for the inspection and examination of the fire scene are countless, and they vary in accordance with the type, purpose and peculiar conditions existing in and about the structure, vehicle or location where the fire occurs. Each fire must be studied on its own individual set of conditions and circumstances. Check lists for arson investigation exist but there is no set rules or a guide that the investigator can depend on exclusively. Even the best, experienced arson sleuth can overlook the most obvious points at a fire, but this knowledge brings him back repeatedly to the scene until he is satisfied that he has covered everything.

Cause and origin

Since the fire scene is the point of departure, it is surely the key to establishing and determining the likely cause and origin. Recently in Texas there were instances of a demented occupant and an overinsured owner carrying a shotgun, establishing the point of departure without question. Even when burning is complete and only tbe ashes remain along with charred metal objects, a successful examination of the scene can be made. The removal of special articles and appliances from the building prior to the fire is an interesting avenue for investigation. Such removal may be developed by witnesses who saw or aided in the removal, or by the failure of the early search to reveal the indestructible articles. Several months ago the finding of a water heater, kitchen sink and commode lying in a backyard of a house that had been destroyed while the occupants were out, aided materially in securing a confession and indictment. Another trick of the arsonist is to stock the premises with a load of junk items which are itemized on the claims at a much higher value.

Accidental fire

Among tbe most difficult of fires to pinpoint as arson are those involving closets, waste baskets, electric irons, defective wall switches, water heaters and similar setups that provide a handy excuse for the so-called accidental fire. Such planned excuses are doubtless often accepted by investigators with only cursory examination of the physical evidence available, which, if carefully inspected, may be found to completely refute the excuse.

An extended investigation of a totalloss fire in northeast Texas developed information that the suspect had experienced two total-loss dwelling fires in Oklahoma during the past three years and that a third dwelling owned and occupied by this suspect on the same farm had been damaged by fire. This last fire apparently had its origin within or near an electric wall switch. Early extinguishment of the fire and an inspection of the attic above it disclosed an open container of gasoline directly above a “defective wall switch”—in a new home that along with the entire farm was up for sale.

Removal of wallboard or plaster around wall switches or other electric wiring should be closely investigated. Such investigation often discloses that the wiring has been cut rather than burned, such cutting being evidenced by sharp ends and marks on the wire rather than balled ends where wires have burned. Such planning often discloses that both the hot and ground wires have been cut near the same point where access was gained prior to setting a fire in the area. Closer inspection may also lead to the discovery of insulating paper dropped within the wall and bits of, or the remains of paper, hay, excelsior or other materials.

Complete search necessary

Casual and hurried inspections of fire scenes with inadequate lighting may result in missing or overlooking the most obvious instruments and materials used by the arsonist. Several years ago the writer and others on returning to a fire the second time, found that due to darkness and carbon deposits we had failed to find a halfbale of soot-covered hay, unbumed, that had been carefully packed around and behind a water heater in a dark closet. The first inspection of the premises had revealed a trace of hay ashes on the ground beneath the seat of the fire in another area of the building where the closet floor had burned through.

It is of extreme importance that even though a single point of origin and extinguishment is found, that a complete search of the building including roof and attics be made. Often self-extinguished fires which occurred on a prior attempt, or simultaneously with the extinguished fire, are found along with marks of work done in preparation. Trails, fire traps, infernal mechanisms, plants for spontaneous ignition and numerous other commonplace contrivances must be carefully sought and located. Bits of information concerning recent defects and failures of heating units and other household appliances may be gathered from occupants and others, which when pieced together may establish cause and origin and save time.

Travel of fire important

The path of burning requires careful study since it will assist in clearing up possible confusion in the mind of the investigator in determining the exact seat of origin. For example, a fire originated from the electrical failure of a thermostat located on the mezzanine floor at the rear of the building having a very shallow attic. This attic opened into a much higher and larger attic in an adjacent structure, to which the fire spread and burned through the roof before breaking through the roof of the building of origin—presumably because of the greater air supply in the larger attic. Therefore the path of burning as affected by the air (oxygen) factor of the triangle must be considered. Similarly the spread of a slow fire into an area of potent fuel may create confusion as to the seat.

The element of heat is often a more confusing factor than the other two elements of the fire triangle. Investigators are well acquainted with spontaneous ignition and the confusion it often presents. They know that excessive quantities of gas may ignite at a point far removed from the area of a violent explosion with little, if any, sustained burning at the area of explosion due to a mixture that is too lean or too rich.

Search in neighborhood

Neighborhood survey outside the structure and on adjacent and nearby premises should be routine in the investigation of all fires and explosions. One is never able to predict what the disgruntled or envious neighbor, or the honest and right-thinking citizen may have to offer. The survey may also bring to light a paint bucket in a trash barrel which may provide the answer to stains found marking the trail of the torch. All suspected and connected substances may fit smoothly into the picture puzzle to establish a true answer. The investigator shouldn’t be casual or hit and miss. Seek all possible connecting physical evidence to fully connect and identify the probable suspect to the cause and origin of the fire. Elementary procedures such as searching the building to determine the absence of treasured family mementos, old photographs, prized china, etc., should not be overlooked.

Within a building of whatever type or use, there is one item that has always been found necessary and that is the clearing and removal of debris to examine the floors. If this isn’t done, valuable information pertaining to the possible use of liquid and powdered accelerants may be missed. Experienced people are familiar with the curved patterns of charring that only flammable liquids can make and of the peculiar patterns often produced by magnesium, powdered aluminum and similar materials. No less important is the careful removal of dirt and dust accumulations in flooring cracks, the removal of liquid-soaked timers, rags, clothing and other materials which may hold remains of suspected accelerants.

At the fire scene, and during its inspection, the tools for gathering evidence and the necessary containers to preserve the evidence should be in readiness and used. Finally, the most important characteristic for the successful arson and fire investigator to possess is the willingness and energy to dig. The task of the investigator at the fire scene calls for work and getting dirt and soot-covered. These qualities, along with a keen sense of observation and the greatest possible knowledge of the fire triangle, are prime requisites for the successful investigation of fire.

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