Investigating Arson — What to do When There’s Not Much Left

Gareth Williams

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Mar 12, 2021

The private sector fire investigator will often arrive at a fire scene to find the scene already extensively searched and disturbed. This may be days, weeks or even months after the fire occurred. This is particularly true in the investigation of deliberately lit fires, where there may have been a thorough police and/or fire service excavation of the site. Other private sector fire investigators instructed by other parties (for different insurers, etc.) may also have carried out their on-site inspection on previous days.

Fire investigation can be difficult enough even when dealing with an undisturbed scene. The interpretation of fire patterns and fire spread is made significantly more arduous and carries potential for erroneous conclusions to be reached, when evidence has been removed, re-located or damaged.

As a general rule, fires destroy evidence as they progress rather than the traditional aspect of other crime scenes, i.e., the greater the time the event proceeds, the more evidence will be present. Combined with the fact the necessary extinguishment and overhaul on site by firefighters also disturbs the scene, the fire investigator is already on the back foot in some respects.

Gathering Evidence

That does not mean that it’s time to throw your hands up in despair or call it an early day. The start of evidence gathering can begin. It is important to try and gather as much information as possible prior to commencing the on-site investigation. The extent of information that the relevant police or fire service investigator is willing or able to share with you will vary wildly depending on the jurisdiction, their formal procedures, the manner in which you have approached them, their personality and whether they are familiar with you. Some public service investigators will be reluctant to talk to you at all, while others will be keen to discuss the case and share findings. Others may also offer the classic line “Off the record …..”. Regardless, the private sector investigator must be mindful and respectful of the procedures the public sector investigator has to follow.

This evidence and information sharing is a two-way street. If the private sector investigator is able to provide useful information or evidence to the public sector investigator, there is a greater chance they will be willing to share information in return. Even if there is little information that is able to be shared in terms of witness interviews, or whether there are suspects or anyone has been charged, the crucial information that needs to be established early on is whether anything has been taken away from the scene.

Utilize the Scientific Method

It is important to realize that although the fire scene may have been heavily disturbed and excavated, the normal procedure of utilizing the scientific method should still underpin your on-site investigation. The scene should still be documented thoroughly, with notes, photographs and video recordings. Witnesses should still be spoken to, and other sources of evidence, such as alarm log data and CCTV footage should still be retrieved if available.

All fire investigators have an on-site goal of determining origin and cause, that is: where the fire started, what was the ignition source, what was the first fuel ignited and how did they come together? The private sector investigator may also have additional factors to consider, depending on who the client is, and whether there are specific policy conditions that need exploring.

Just because the scene has been heavily searched, it does not mean there is no evidence to be found. Depending on the extent and skill of the previous inspection, there may be crucial evidence remaining in debris that has already been searched by others, or in areas that were not originally searched.

The use of an on-site arson checklist can greatly aid the investigator in considering a range of factors that may indicate the fire has been deliberately lit. In combination with the standard fire investigation methodology, valuable information can be relayed to the client that may assist in recovery, repudiation prospects or liability claims.