The Fire Officer’s Responsibilities at Incendiary Fires

In this month’s column, we will discuss the fire officer’s responsibility in assisting the fire investigation units at the scene.


As the fire officer you should note the location and extent of the fire and any ventilation holes or openings made. Keep in mind that ventilation plays a major role in fire spread and development. Did the fire department have to force entry or was the structure open? Look for forcible entry tools that were left behind such as pry bars or screwdrivers. If these items are found, they must be protected as evidence. Note any prior structural damage such as holes in floors, walls or ceilings. Make a mental note of any entry or egress problems that would hamper fire department operations. Remember what tactics were used for extinguishment. What was the operating mode, offensive, defensive or no attack? All of these questions should be part of the interview of the first arriving company by the fire investigator.

Overhaul Operations

For fire officers and firefighters overhaul is as important as the extinguishment of the fire. Officers need to make sure that the fire is completely extinguished to prevent a rekindle. If a rekindle occurs, it is often worse than the original fire because the structure has been compromised. Overhaul can be preformed in two phases, pre-control and post-control. Pre-control overhaul is conducted when the fire is still burning and still has control. Post-control overhaul is conducted after the fire is under control. Fire department members need to extinguish the fire before the interior examination can begin. Remember, the fire investigator may benefit from being present during overhaul operations.

Fire department personnel should make every effort to avoid any unnecessary damage during overhaul operations. The fire officer should supervise members conducting overhaul operations and ensure the investigator is aware of, and approves the removal of, any furnishings or building contents from the structure. It is the officer’s responsibility to ensure that all the contents at the area of origin are not thrown out the window or placed on the front lawn. During overhaul, areas of the fire building need to be opened to check for fire extension. However, members should use caution and know when to stop. The use of a thermal imaging camera (TIC) will assist with this task. The officer should stop firefighters from removing all the sheetrock and plaster from the studding. The reason for this is that the investigator will need to examine the fire patterns. Fire patterns are the measurable or visible effects that remain after the fire. The interpretations of fire patterns are valuable for identifying the potential ignition source. The key to successful overhaul operations is training. The fire investigator should conduct training and/or put out a memo on fire patterns and overhauling for fire investigation.

Indicators of the Incendiary Fire

The incendiary fire is defined as a fire that has been ignited deliberately in which a person knows the fire should not be ignited. The fire officer may come across the indicators of an incendiary fire during suppression operations or overhaul. The company officer should make notification to the incident commander as soon as any indicators of an incendiary fire are found. There are many incendiary fire indicators that the officer should be aware of and thus take steps to protect and preserve the evidence for the fire investigator. Let’s define some of the indicators.

Multiple Fires: Non-related fires that are burning simultaneously with different areas of origin. Fires that are on different stories of the structure at the same time, that are not connected. Fires that are located in different rooms of the structure that are not connected. I responded to a late-night fire a few years ago. Upon arrival, we had three commuter buses that were fully involved and about a half-mile away we had a storage container burning. This is an indication that you may have a set fire. The fire officer should request the investigator to respond when multiple fires are burning.

Trailers: Trailers are used to spread the fire from one area to another. They can be used on stairways to move the fire from story to story. They can be used on floors to connect fires. They can be used with a time-delay device. Time-delay devices are used to allow the firesetter to leave the scene. If trailers are found, it is strong evidence that it is an incendiary fire. Some of the materials used for trailers are paper/newspaper, clothing/rags, and ignitable liquids.

Incendiary Devices: These devices are used to initiate the incendiary or arson fire. Examples of devices are firebombs, Molotov cocktails, matchbook devices, candles in the area of origin, and balloons with ignitable liquids. If any incendiary devices are found, secure the area to protect the evidence. Moving or touching the devices can be dangerous and can result in an explosion or ignition of the device.