Fire investigation for the First Responder

CarolinaFireJournal - Zane D. Poindexter
Zane D. Poindexter
04/26/2010 -

One of the most important components to a successful fire service response is a properly completed origin and cause fire investigation. We state this as fact for two important reasons: to recognize an intentionally set fire and to subsequently assist with placing those individuals responsible into the criminal justice system, and also to properly identify certain dangerous practices or faulty equipment that may spark accidental fires. Neither of these end results could be possible without proper scene preservation and other important functions conducted by the first responding crews.


Scene preservation

If proper scene preservation is not a priority, and there is little thought and direction as to how to proceed after the fire has been deemed “under control,” the case may suffer. Fire pattern analysis, evidence collection and a complete scene examination may become much harder, or even deemed impossible by the investigator, dependent upon each individual scene.



It is of the utmost importance, especially in a fire scene that may involve a criminal activity, that room contents are left as they were discovered so they can be captured in their original condition by either photography or video. This is important because the fire investigator or law enforcement official must be able to produce visual images of the scene in a courtroom to develop their case, and to help prove to a judge or a jury that a criminal activity actually did occur. As a good rule of thumb, treat every scene as a crime scene until proven otherwise so that a mindset is established and good habits are learned.     

Information and Fact Gathering

Once extinguishment has taken place, we begin the process of finding out who, what, where, when, how and why. Asking the right questions to the owner or occupant can immensely help the investigator determine where he/she may need to begin. Recording some basic information at the beginning is necessary to start the investigation. One key area to focus on is getting information from the owner or occupant. Recording the occupant’s name, age, race or ethnicity, address, phone numbers and employer could prove to be very important later in the investigation. It is also necessary to obtain this information from everyone at the incident at the time that it happened so that investigators can contact them if the need arises. 

Another reason to get this information quickly is that some of the individuals involved seem to disappear. This could mean a couple of things: either they have been swept away by family, friends or someone trying to help with their situation, or they might have been involved, either accidentally, or intentionally, in the cause of the fire. It is crucial to get their information and story of what happened quickly before they find reason to leave the scene.

Identifying and documenting crucial interior operations performed by fire suppression crews can greatly assist in the investigative process as well. Certain key strategical maneuvers such as placement of the first in hand line, which doors were forced and which doors were found unlocked, location and the behavior of the fire in the structure are components that can all be used in conjunction when we start attempting to place all the pieces of the puzzle together.

A recommended practice would be to document these things as soon as possible during the scene so that as when engine companies are being released, the incident commander has a grasp on what was done and who it was done by so he/she can relay this information to the investigator, if necessary.

Fire Cause Determination

There are two causes of fire: accidental which includes providential (acts of God) and incendiary or intentionally set fires. The recognition of both types of fire causes requires the ability to identify certain fire patterns, the understanding of fire behavior and what ignition sources are present, if any. 

Accidental fires have multiple causes. Many of these fires are a result of an equipment misuse or malfunction such as overloaded extension cords or faulty wiring. Carelessness is also responsible for a large number of accidental fires. Cooking equipment left on, or not attended, results in most fire causes that are determined to have an origin in the kitchen.  These types of fires will often result in the victim’s own admission of their carelessness. However, it also sometimes leads to victims blaming faulty equipment or producing other scenarios that are sometimes hard for us to justify. Being able to wade through the evidence found on scene versus words of victims who are not willing to accept responsibility can prove to be a challenge.

Incendiary fires are intentionally started or allowed to start. Arson is a type of incendiary fire, but all fires that are intentionally set are not arson. Arson is a legal term that refers to a specific type of burning offense. Intentionally set fires will usually have some indicative traits and discernable features, such as the presence, or smell, of ignitable liquids in the area; multiple fires or multiple points of origin; irregular burn patterns, either on flooring or walls; and the presence of trailers. A trailer is any combustible or flammable material used to spread a fire from one point to another. These can range from flammable liquids that have been poured to interconnecting combustible linens or paper products.  

Accidental Source Elimination

During the initial investigation, it is a good practice to begin to rule out all accidental sources of the fire. When the room, or area of origin, has been determined, the examination of all accidental sources in the room can be a guide in locating the source of the fire. Locate all electrical sources and other accidental sources such as candles, heaters, appliances, etc. in the area and examine them for failure, misuse or carelessness. Even when an incendiary fire is suspected, it is still a good practice to rule out all potential accidental sources in the room of origin and have those sources photographed to document your findings. This gives you the ability to describe why each was not the cause of the fire. Being prepared to answer these questions could make it much easier in the courtroom if your case entered the judicial system.


The first responder is often in the best position to make critical observations and conclusions regarding a fire. The observations of the first responder during various stages of an incident are crucial to the development of the investigation and the case that the investigators are handed. From the initial call until the overhaul phase has been completed, the first responder is exposed to countless stimuli, many of which can help the company officer or fire investigator make a determination into the origin and cause. Without the first responder’s full attention to detail, valuable information and evidence could be lost or destroyed.

Zane D. Poindexter has more than 16 years of fi re service experience and is currently an Assistant Fire Marshal with the City of Winston-Salem where he frequently teaches fi re investigation and fi re prevention classes. He has obtained certifi cations as a North Carolina Certifi ed Fire Investigator, NAFI Certifi ed Fire and Explosion Investigator and NCSFA Advanced Firefi ghter. Poindexter is also a Live Burn Instructor and Fire Offi cer Level III. He can be reached at [email protected]
Comments & Ratings

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New Comment 
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