Investigating the cause of a fire is a routine function of fire departments nationwide. A fire investigation and determination of cause are important for two primary reasons: there are deliberately set fires and persons who should be held responsible for the arson crime, and there may be trends identified in accidental fires that cause awareness or a manufacturer's recall of a faulty component. These two aspects of fire cause are responsible for many firefighter and civilian injuries and deaths. By accurately determining the cause of a fire, the company officer is fulfilling a task that will translate into a safer society in which to live.
The Uniform Fire Code (UFC) grants fire departments the authority to investigate the cause of fires that they extinguish. UFC Section 104.2 states, "The fire department is authorized to investigate promptly the cause, origin and circumstances of each and every fire occurring in the jurisdiction involving loss of life or injury to person or destruction or damage to property and, if it appears to the bureau of investigation that such fire is of suspicious origin, they are authorized to take immediate charge of all physical evidence relating to the cause of the fire and are authorized to pursue the investigation to its conclusion."
Prior versions of the UFC used the language "shall" instead of "is authorized" regarding the investigation of fires. This may have been the result of the emergence of dedicated fire investigation units, whose fire investigations are usually more comprehensive than the investigation performed by the first responder. The issue of whether a fire department was required to utilize its dedicated fire investigators for all fires due to the language in the UFC may have presented the potential for liability for fire investigations performed at the engine company level.
This is not to suggest that fire investigators assigned to engine companies, effectively multi-tasking, are as qualified as a full-time fire investigator. The comparison is to the company officer, whose primary duty is the suppression of the fire, with the need to determine cause for the statistical documentation required for all fire responses.
Right of Entry
A fire scene is entered by fire personnel under exigent circumstances, meaning that an emergency is occurring and there is no time to obtain the consent of the occupant or a court order. A part of the fire operations, or exigency, is the need to determine the cause of the fire for public safety. When the exigency is gone, there is no longer a right to enter. Any entries made after the exigency must be conducted under other means of entry; consent, administrative search warrant, criminal search warrant or abandonment.
- Michigan v. Tyler. This U.S. Supreme Court decision involving a fire in a furniture store stated that an investigation may continue for a "reasonable period of time" after the suppression of the fire without the need for a criminal or administrative warrant. This is somewhat subjective, but an example would be postponing an investigation to wait for daylight or to stabilize an unsafe structure.
The recognized procedure for conducting an origin-and-cause investigation is the scientific method, which is a systematic approach to information gathering and analysis, with a resulting tested hypothesis. This is the basis for nearly all scientific inquiries and is not nearly as complicated as it seems.
The steps of the scientific method are:
On the fire scene the first three steps are completed by receiving the request to respond from the incident commander, systematically examining the scene from the least damage to the heaviest damage, and interviewing firefighters and witnesses. This hopefully provides enough data to develop a hypothesis, or opinion, on where the fire started and what caused the fire to occur in this location. By testing the hypothesis; using the behavior of fire and witness statements, a final hypothesis, or opinion, may be determined. In some cases, the test may include laboratory testing, other scientific procedures, or a more comprehensive investigation.
Origin & Cause
During the application of the scientific method, the goal is to identify an area of origin and the event that caused the fire. The cause cannot be determined if the area of origin is not identified. By determining an area of origin, the company officer or investigator can then identify potential ignition sources that exist within the area defined. If the area of origin is confined to a small area, there will most likely be fewer potential ignition sources.
However, the area of origin must contain all aspects of an area defined primarily by fire behavior, based on the examination of fire flow and fire intensity patterns. The area of origin must not be made small for convenience. Depending on the fire behavior observed and the amount of fire damage, the area of origin can be very isolated or an entire room, sometimes multiple rooms. There is a point where the amount of damage eliminates the ability to determine a cause, or even an area of origin.
When the area of origin is determined and the potential ignition sources are identified, a systematic examination and evaluation of each must take place. An ignition source must be capable of transferring sufficient heat energy to the first fuel ignited. If an ignition source is not capable of transferring sufficient energy to ignite the fuel package, then it would be difficult to support it as a cause, even though it exists in the area of origin. Conversely, if an ignition source existing in the area of origin does have sufficient heat energy to cause ignition, but is determined not to be the cause, the elimination must be supported. There has to be a reason why the ignition source ignited a fuel package and the investigator is tasked to identify not only the heat, fuel and oxygen, but also the event.
An example of multiple ignition sources in a small area of origin is a dresser top that has an ashtray and smoking materials, candles, incandescent lamp, radio and small electric space heater. Under the right conditions, any of these ignition sources could ignite an appropriate fuel package, but only one will have been the cause. To determine a cause in this fire, the cause must be identified and the other ignition sources must be eliminated. Physical proof of one cause is helpful in eliminating others, as is the inability of an ignition source to transfer enough heat to set fire to the first fuel ignited.
Myths & Misconceptions
There are many fire indicators that once were valid, but aren't now due to the changes in fuel packages found in modern structures, or never were valid and have been disproved in controlled studies. Due to the synthetic materials in modern furnishings, it is customary for a fire to spread rapidly throughout a bedroom-sized compartment. Post-flashover conditions are commonplace. Note that fire behavior, being a chemical reaction and process, remains unchanged. It is the materials burning that are different. The following fire indicators or conditions illustrate how fire progression has changed.
- Depth of char/alligatoring. A timeline used to be attributed to the depth of char found on wood framing. An investigator supposedly could estimate how long the fire burned by how deep the charring was. This has been proven to be false. Where the fire started and the intensity of the fire will dictate how much charring will occur, further influenced by fuel configuration and ventilation. Simply put, if a match is placed against a piece of wood for one minute, it will cause less damage than a torch placed against the same piece of wood for one minute. It is simply a matter of time versus intensity; a long-duration, low-intensity event can present very similar to a short-duration, high-intensity event. In both cases, there will be more damage to vertical arrangements than to horizontal arrangements.
Depth of char is a very important indicator and can be used to show trends of fire travel; that is, all things considered equal, the fire will tend to cause more damage where it burns the longest.
Alligatoring is the rounded char blisters that occur as wood burns. If the blisters were large and shiny, it was thought to be an indicator that an ignitable liquid was used. This is untrue. An examination of various wood members in a fire scene will reveal that different pieces of wood show different sizes of char blisters while exposed to the same fire. There is no significance to the appearance of the alligatoring.
Company officers should be aware that their opinions carry great weight with the legal system. The fire department personnel are often considered the only unbiased party in a legal proceeding. When the company officer lists a cause on a fire department incident report, it is considered reliable and has often been the basis for a subrogation claim against a manufacturer or contractor.
Manufacturers will vigorously defend their products, using an array of lawyers and experts to examine the case. This may be to defend against a single large loss or to prevent a trend of future litigation or the recall of a product. When the company officer is subpoenaed to testify on the origin and cause, the counsel representing the manufacturer or contractor will expect to hear how the cause was determined and how other ignition sources were eliminated. At the same time, the claimant attempting to recover a monetary judgment against the manufacturer or contractor will be expecting that the company officer is able to support the claim of responsibility. A clear line of right or wrong, win or lose is most times not the issue and the case is determined on degrees of responsibility. The testimony of the fire department personnel is very important, whether supportive or damaging, and the examination can be intense.
As is the case with a fire investigator, a company officer should be prepared to list the cause as unknown or undetermined if one is not identified or if other ignition sources in the area of origin are not eliminated.
Publications & Resources
Although there are numerous publications regarding the investigation of fires, having just a few will cover all aspects and issues involved. The most recognized texts are NFPA 921, Guide for Fire and Explosion Investigations, published every three years by the national Fire Protection Association, and Kirk's Fire Investigation by John DeHaan. Firefindings, a quarterly subscription publication, also contains excellent and accurate material. Lee Cole's Investigation of Motor Vehicle Fires contains specific techniques and issues pertaining to vehicle fires.
The websites of the International Association of Arson Investigators, www.firearson.com, and Firefindings, www.firefindings.com, have bulletin boards where investigators can post questions and receive replies from other investigators.
Fire investigations are complex ventures. Careful consideration of fire patterns and physical evidence on the scene, direct and circumstantial, must be evaluated in totality to successfully determine where the fire started and what ignition source was the cause. The opinion of the company officer can be the basis for a multimillion-dollar lawsuit against a party considered responsible years after the fire occurred. The responsibility to determine cause should be approached with this thought; what is entered on one line of a fire incident report can result in years of legal action.
Our opinions and reputations are valuable. Although municipal fire investigators as well as company officers are concerned with identifying and investigating criminal actions, they must also be proficient at recognizing accidental fire causes in order to fulfill the elimination process during the scientific-method/systematic-approach investigation.
Fred Herrera, CFI, is an investigator and 25-year veteran of the San Diego Fire-Rescue Department. He is a supervising captain of San Diego's Metro Arson Strike Team (MAST) and also conducts origin-and-cause investigations for Engineering & Fire Investigations (EFI). Herrera holds International Association of Arson Investigators (IAAI), National Association of Fire Investigators (NAFI) and California Conference of Arson Investigators Certified Fire Investigator certifications. He has an associate of science degree in fire science and is a licensed private investigator.