Arriving at the Fire and/or Arson Scene: Evaluating the Scene

Once a lead investigator arrives at the scene to relieve the first responders, he or she should evaluate the scene, identify witnesses and survey what must be done. The lead investigator must:

Note: This section of the guide is intended for the individual responsible for the investigation of a fire incident. At the time the scene is determined to involve an arson or other crime, the investigator must address legal requirements for scene access, search and evidence seizure.

Contact first responders and establish presence. The investigator should meet with the incident commander and first responders to assess previous events and the current status of the fire scene, make introductions, identify essential personnel, and determine scene safety and integrity issues.

The investigator should:

  • Identify and contact the current incident commander and present identification.
  • Conduct a briefing with the incident commander to determine who has jurisdiction and authorization (legal right of entry) and to identify other personnel at the scene (e.g., law enforcement, firefighting, emergency medical services, hazardous materials personnel and utility services personnel).
  • Determine the level of assistance required and whether additional personnel are needed.
  • Determine initial scene safety prior to entry through observations and discussions with first responders. Consider environmental as well as personnel safety concerns. Assess changes in safety conditions resulting from suppression efforts.

Define the scene's boundaries. The investigator should perform a preliminary scene assessment, determine the area in which the site examination will be conducted and establish the scene perimeter.

The investigator should:

  • Make a preliminary scene assessment (an overall tour of the fire scene to determine the extent of the damage, proceeding from areas of least damage to areas of greater damage) to identify areas that warrant further examination, being careful not to disturb evidence.
  • Inspect and protect adjacent areas that may include nonfire evidence (e.g., bodies, bloodstains, latent prints or tool marks) or additional fire-related evidence (e.g., unsuccessful ignition sources, fuel containers and ignitable liquids).
  • Mark or reevaluate the perimeter and establish the procedures for controlling access to the scene.

Identify and interview witness(es) at the scene. The investigator should determine the identities of witnesses and conduct interviews.

The investigator should:

  • Contact the incident commander, identify first responders and first-in firefighters, and arrange to document their observations either in writing or through recorded interviews.
  • Determine who reported the fire. Secure a tape or transcript of the report if available.
  • Identify the owner of the building/scene, any occupants, and the person responsible for property management.
  • Identify who was last to leave the building/scene and what occurred immediately before they left.
  • Identify and interview other witnesses (e.g., neighbors and bystanders) and record their statements.

Assess scene security at the time of the fire. The investigator should determine whether the building or vehicle was intact and secure and if intrusion alarms or fire detection and suppression systems were operational at the time of the fire.

The investigator should:

  • Ask first responders where an entry was made, what steps were taken to gain entry to the building or vehicle, and whether any systems had been activated when they arrived at the scene.
  • Observe and document the condition of doors, windows, other openings, and fire separations (e.g., fire doors). Attempt to determine whether they were open, closed or compromised at the time of the fire.
  • Observe and document the position of timers, switches, valves, and control units for utilities, detection systems, and suppression systems, as well as any alterations to those positions by first responders.
  • Contact security and suppression system monitoring agencies to obtain information and available documentation about the design and function of the systems.

Identify the resources required to process the scene. The investigator should determine what personnel may be required to process the scene according to National Fire Protection Association (NFPA) 921 and other recognized national guidelines.

Note:Except in the most obvious cases, the determination of a fire's origin and cause may be a complex and difficult undertaking that requires specialized training and experience as well as knowledge of generally accepted scientific methods of fire investigation.[1] The investigator must either have appropriate expertise or call upon the assistance of someone with that knowledge.

The investigator should:

  • Identify a distinct origin (location where the fire started) and an obvious fire cause (ignition source, first fuel ignited, and circumstances of the event that brought the two together).
  • If neither the origin nor the cause is immediately obvious, or if there is clear evidence of an incendiary cause, the investigator should
    • Conduct a scene examination in accordance with NFPA 921 and other guidelines.
    • Seek someone with the expertise required.
  • Know when to request the assistance of specialized personnel and to obtain specialized equipment as required to assist with the investigation. Standard equipment should include the following:
    • Barrier tape.
    • Clean, unused evidence containers (e.g., cans, glass jars, nylon or polyester bags).
    • Compass.
    • Decontamination equipment (e.g., buckets, pans and detergent).
    • Evidence tags, labels and tape.
    • Gloves (disposable gloves and work gloves).
    • Handtools (e.g., hammers, screwdrivers, knives and crowbars).
    • Lights (e.g., flashlights, spotlights).
    • Marker cones or flags.
    • Personal protective equipment.
    • Photographic equipment.
    • Rakes, brooms, spades, etc.
    • Tape measures.
    • Writing equipment (e.g., notebooks, pens, pencils and permanent markers).

Note: If the scene involves arson or other crimes, the investigator must address legal requirements for scene access, search and evidence seizure.

  • Recognize the interests of parties that may be affected by the outcome of the investigation and avoid jeopardizing those interests by taking steps to protect evidence. These issues include spoliation[2], subrogation[3] and third-party claims.


[note 1] As stated in NFPA 921, the scientific method consists of defining the problem, collecting data, analyzing the data, developing hypothesis (e.g., what could have caused the fire), testing the hypothesis and considering alternative hypothesis.

[note 2] Damage or loss of evidence that would compromise a legal case.

[note 3] Recovering damages by a finding of fault; finding that the cause of the fire was failure of some product or system.

Date Created: June 1, 2009