First-arriving firefighters with the right mindset can provide a wealth of information to assist in fire investigation and legal proceedings.

A CASEBOOK FROM an average fire investigation usually lacks documentation by emergency service personnel who first respond to the scene. The observations of these individuals can be just as important to the investigation or an ensuing court trial as the notes, photographs, and evidence taken by investigators after the fire has been extinguished.

Careful documentation of observations made by first-responding firefighters is beneficial in a number of ways and may substantiate the investigator’s findings. On the other hand, any discrepancies might prove embarrassing to the district attorney and the fire investigator if they are discovered during court testimony. These observances can only be made at the first stages of the incident by responding firefighters, yet they may affect a trial’s outcome months or years later.

Granted, a civilian eyewitness to an early stage of the fire can provide much needed information for the fire investigator, especially in cases where the fire causes extensive structural damage and few clues remain. Investigators do not hesitate to tap this resource by requesting written documentation from them. It is very likely that this knowledge will provide valuable clues as to the area of fire origin and possibly the circumstances surrounding the cause of the fire.

However, investigators are reluctant to request documentation from those trained to suppress the fire—personnel who, by their very actions on the fireground, possess detailed knowledge of both the exterior and interior of a structure. Some argue that firefighters are not fire investigators and they don’t have the expertise necessary to assist in the investigation process. While it may be true that fire service personnel at the scene of a fire may not be the designated or recognized fire investigators, they still have valuable information to share.

The fire service personnel who arrive first at the scene, long before fire investigators, see and experience the fire scene from the time they arrive until the time they pick up the hose and return to quarters. Each working level of personnel, from the incident commander to the firefighter on the hoseline, has a different perspective of the emergency scene. When added together, their insights provide a reliable overview of the fire area and its surroundings. Their documentation is just one piece of a large puzzle—and is an accurate point of reference for a later investigation.


The following are just some examples of fire behavior and structural conditions during the early stages of response that firefighters should observe for later use in the fire investigation.

Smoke. Most civilians describe the color of smoke as “black.” Black smoke is possible when some types of petroleum products are involved in a fire, but civilians tend to offer this description for slow smoldering fires, grass fires, hay fires, and Class A fires. Firefighters have a better understanding of smoke colors and can more accurately describe them.

The color of smoke can indicate what fuels and combustibles are involved in the fire. Light-colored smoke (white to gray) often indicates the presence of Class A-type materials—including vegetable compounds such as hay or grass. Gray-to-brown smoke usually suggests wood, paper, or cloth-type materials and that it is a slow smoldering fire. Brown-to-very-black, thick smoke often signals the presence of oils and petroleum products such as turpentine, kerosene, gasoline, rubber, and foam products. Remember, as a fire becomes more intense both in size and duration, it spreads into its surroundings and modern-day furnishings (most of which contain petrolem-based products or other plastics) and creates a large amount of black smoke.

Flames. In most accidental structure fires, the flame colors generally range from yellow to orange but also have a corresponding smoke color of a lighter tint, usually gray to brown. In fires that have been accelerated by the use of some type of petroleum product, the flame color in the early stage tends to run from yellow to dark red, with very black, thick smoke. This is unusual and should raise suspicions of a flammable liquid-accelerated fire.

Venting. It is important to take note of the venting of the fire and smoke and its location on arrival. Firefighters know that if the fire has vented itself, the interior will be more tenable, making rescue and extinguishment more likely. The fire investigator also is concerned with venting in this early stage of the fire. If the fire is venting, it may give clues as to the area of origin or indicate a longer burn time in a certain area. This is not always the case, though. It is possible for venting to occur far from the area of origin, away from the main body of the fire, but again, this could only be determined by early-arriving personnel.

Forced entry. Open or unlocked doors or windows, or other signs of forced entry, can indicate an incendiary fire. Fires are often set in structures to hide evidence of burglary, vandalism, or other crime-related activities.

Fire service personnel, by using their own forcible entry tools to get at the fire area, may destroy or cover up tool marks from a burglary. But if they note the different tool marks, personnel trained in identification can compare the marks later. In any case, the condition of the entrance door, locked or unlocked, can only be attested to by the first-arriving firefighters.

Fire tactics. Proper fire attack is generally from the unburned side of the fire, forcing the fire backward onto itself for extinguishment. When this is not practical or possible, firefighters use other means of fire attack. For example, in a fully involved structure, firefighters may attack the fire from more than one side at a time. Some firefighters may direct the hose stream through a window and attack from an exterior position. This usually forces some heat and the products of combustion from an involved area to a previously uninvolved area. It may create false flame patterns, charring, and heat damage. Fire suppression personnel can help the investigator understand the fire travel through a structure by remembering from what direction they attacked the fire and what size hose stream they used.

It is also important to note in what order extinguishment occurred. Often fires continue to burn in one area longer than in other areas. Generally, the longer burning time is located nearer the area of origin, as is a deeper charring pattern with greater localized destruction of the surrounding area. This area is normally extinguished later in the firefighting, as fire suppression efforts usually begin on the outer fringes of the fire area and continue back toward the area of origin.

The order of extinguishment and the “charring time factor” are important considerations for the fire investigator. If, for some reason, the area of fire origin was extinguished prior to other areas, then other areas may have a deeper charring and more localized destruction and may contradict the general rule that the deepest charring usually is located at or near the area of origin. Investigators would later search for a logical explanation for the deeper charring occurring away from the area of origin. Fire suppression personnel could then explain their actions and the order that extinguishment was completed.

Burning characteristics. Fire personnel may notice the fire burning in an unusual manner. They know that placing a stream of water onto a burning combustible should extinguish the flame by lowering the combustible’s ignition temperature. But a stream of water applied to fire on a normal combustible started by flammable liquids behaves quite differently. Flammable liquid residue may float to the surface of the water and reignite (flash back), continue flaming, and spread. A flashback may indicate that some type of flammable liquid was used to ignite and accelerate the fire and cause it to spread unnaturally.

If flammable liquids were used, firefighters might notice the odor of such substances after removal of their breathing apparatus in the latter stages of overhaul. It is important to make a mental note of these strange odors, since they might no longer be detectable by the time the investigator arrives. Documentation of such observances will refute a defense claim at a trial that flammable liquid was introduced into the fire scene after the fire suppression personnel vacated the area but before the investigator arrived.

Fire spread. Firesetters create certain conditions in structures to help spread the fire. The materials used to create such conditions (normally called trailers or plants) may include flammable liquids, flammable liquid-soaked rags running from one point to another, lengths of wax paper, and strewn newspapers. If the fire increases in size, these items may become very difficult for the investigator to find.

Another way to encourage fire spread throughout a structure is by altering the structure components themselves. Some of these may not be obvious to the untrained eye: fire doors propped open or made inoperable, open windows and doors, sprinkler system tampering, and alarm system tampering. Again, these conditions may be difficult for the fire investigator to detect in the obliterated structure.

Electricity. The fire investigator usually checks the electrical panels to see which breakers may have been tripped during the course of the fire. Many times, though, someone turns off the main breaker on the panel as well as the secondary breakers during fireground operations, and when the investigator arrives for the investigation and checks the panel, the switches are in the “off” position. Unless the investigator questions the firefighter who switched off the breakers, most likely he will not be able to determine which had been switched off during the course of fire operations.

Proper fireground safety requires that the electrical panel be switched off. Fire personnel responsible for this function know what other breakers were previously tripped. Investigators need this information, especially if they suspect an electrical problem as the possible fire cause.

Overhaul. Firefighters often remove furnishings and other contents from the fire area during salvage and overhauling operations, depending on the extent of the fire. The investigator often returns some of the contents to their original locations to better understand the fire behavior in the structure. This is much more easily accomplished if the firefighters can remember where the items were originally located.


Can firefighting forces help with the investigation process? Yes, of course! Both the fire investigator and the firefighter can benefit from each other.

If fire service personnel arriving on the scene of a fire remember what to look for and pass that information on to the fire investigator, it will make the investigation process smoother and faster. It also will be helpful in the event of a court trial. The firefighters and the fire investigator can and should be partners in the investigation process, and such a partnership will prove invaluable in future investigative efforts.


  1. What was your function at this incident?
  2. What was the color of smoke and/or flames upon your arrival?
  3. From what location(s) was the fire venting upon your arrival?
  4. Were the doors or windows locked or unlocked, open or closed upon your arrival? Did you notice evidence of forcible entry prior to entering the building?
  5. Who conducted forcible entry? What tool was used and the location?
  6. Were any windows or doors covered?
  7. From what direction did you attack the fire? What size hoseline did you use?
  8. On what area did you first put water? What was the last area that you extinguished?
  9. Did the fire behave in any abnormal manner?
  10. Did you notice unusual odors in the area?
  11. Were any conditions created to assist the fire spread?
  12. Did you or were you aware of anyone else turning off the electrical panel? Who? What breakers were tripped prior to turning off the electrical panel?
  13. Were items moved from their original locations that may be of interest to the investigation of this fire?
  14. Is there anyone who may have additional information concerning this fire? How may he or she be contacted?
  15. Think about any statements made to you by an occupant of the fire structure, passersby, or anyone not connected with the fire department who may have a bearing on this fire. Who made the statements, when, and how may they be contacted? (If unable to provide a name or an address, describe the individual as best as possible.)
  16. Draw a diagram of your hose placement and the direction that you attacked the fire. Are there any other items you feel are important?
  17. Do you have any additional information that may be of interest to the investigation of this fire?

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