Fire investigation

Investigating fires

In common with many forensic disciplines, one of the early tasks of fire investigation is often to determine whether or not a crime has been committed. The difficulty of determining whether arson has occurred arises because fire often destroys the key evidence of its origin. Many fires are caused by defective equipment, such as shorting of faulty electrical circuits. Car fires can be caused by faulty fuel lines, and spontaneous combustion is possible where organic wastes are stored.

A fire investigator looks at the fire remains, and obtains information to reconstruct the sequence of events leading up to the fire.

One of the challenging aspects of fire investigation is the multi-disciplinary basis of the investigator's job. As fires can be caused by or involve many ignition sources and fuels, fire investigators need to know not only the science of fire behavior, but also to have a working understanding of many different areas of study including construction, electricity, human behavior, and mechanical devices. For example, if there is a gas appliance at the origin of the fire, an investigator should know enough about appliances to either include or exclude it as a possible cause of the fire. Fire investigators sometimes work with forensic engineers, such as forensic electrical engineers when examining electrical appliances, household wiring, etc.

In the United States, fire investigators often refer to NFPA 921: Guide for Fire and Explosion Investigations (National Fire Protection Association).

Also, Kirk's Fire Investigation by David J. Icove and Gerald A. Haynes has long been regarded as the primary textbook in the field of fire investigation.[1] It is currently in its 8th edition (published in 2017, ISBN 978-0134237923).

Conducting investigations

Fire investigators conduct their investigations using a systematic approach utilizing the scientific method, including the following:[2] When arsonists attack, there is very rarely much evidence left at the scene. However, arsonists usually use accelerants to speed up a blaze. Forensic scientists use technologies to heat samples taken from the scene causing any residue to separate. This sample is then analyzed to determine the chemical structure. Scientists also use other tests such as using liquid nitrogen gas to trap residue which are then analyzed using gas chromatography. The investigator:

  • Receives the assignment and responsibilities
  • Plans the investigation and assembles tools, equipment, and personnel
  • Examines the scene and collects data
  • Collects, tests, evaluates, and documents evidence
  • Applies the scientific method to analyze the information obtained


Spoliation is the destruction or alteration of evidence through intention or ignorance. The mere act of extinguishing a fire can destroy potential evidence of arson or what is also known as an "Incendiary fire." Firefighters are educated that the stream of their fire hose or the use of a Pike Pole can destroy evidence and efforts are made to do what is required to extinguish the fire, while not destroying clues to the fires' origin. A fire investigation was once compromised by a fire fighter turning off the knobs on a gas stove in the interests of safety after a house fire was knocked down. In the following investigation the homeowner's daughter was accused by her father of leaving the stove on after she left the house but there was then no way to accurately determine the position of the burner knobs on the stove. Though there were no criminal issues involved in this fire, this incident of spoliation created a lack of closure for the family and feelings of distrust and animosity within the family members. -FIRE INVESTIGATION by Russell Chandler. Delmar Cengage Learning - Publishers.


The National Fire Protection Association (NFPA), through a document known as NFPA 1033, Standard for Professional Requirements for Fire Investigator, publishes minimum requirements for the knowledge skills and ability of a fire investigator. Principal among these is a 16-point list of areas in which a fire investigator is required to have education beyond high school level. These 16 topics are:

  1. Fire science
  2. Fire chemistry
  3. Thermodynamics
  4. Thermometry
  5. Fire dynamics
  6. Explosion dynamics
  7. Computer fire modeling
  8. Fire investigation
  9. Fire analysis
  10. Fire investigation methodology
  11. Fire investigation technology
  12. Hazardous materials
  13. Failure analysis and analytical tools

Fire scene investigators may become certified through the National Association of Fire Investigators (NAFI)or the International Association of Arson Investigators (IAAI). Both certification programs rely heavily on the content of NFPA 1033 and NFPA 921. Both also require an application process detailing the investigator's education, training, and experience, and successfully challenging a written examination. Certificates are valid for a period of 5 years, at which time an investigator must demonstrate continued participation in the field and a minimum amount of continuing education in order to be recertified.

The National Association of Fire Investigators (NAFI), a professional association of fire and explosion investigators, offer several National Board Certified fire investigation certifications including:

  1. Certified Fire and Explosion Investigator (CFEI),
  2. Certified Vehicle Fire Investigator (CVFI), and
  3. Certified Fire Investigation Instructor (CFII).

The International Association of Arson Investigators (IAAI), a professional group of fire investigators, grants the following certifications:

  1. Certified Fire Investigator (IAAI-CFI) – certified by the ProBoard Fire Service Professional Qualifications System.
  2. Fire Investigation Technician (IAAI-FIT)
  3. Certified Instructor (IAAI-CI)
  4. Evidence Collection Technician (IAAI-ECT)

See also


  1. J.F. Decker and B.L. Ottley, Arson Law and Prosecution, Carolina Academic Press, ISBN 1-59460-590-4, 2009, p. 22.
  2. NFPA 921: Guide for Fire and Explosion Investigations


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