Widget Image
Widget Image
Widget Image
Burn patterns and damage indicators can lead to a fire’s origin.

Determining cause and origin

What happens when the fire is extinguished and the gear is packed away? Is there any thought put to what caused the fire, or where it started? Do you conduct any type of investigation into origin and cause of the fire?

By conducting an investigation into origin and cause there are several benefits that ensue:

  1. If the fire is arson-related, an investigation may lead to finding the origin and cause and eventually the perpetrator of the crime. This may lead to an arrest and conviction, which then means that this cause has been eliminated (the arsonist removed from the community).
  2. If the fire is determined to be accidental – Was it caused by a faulty appliance? Was it caused by a poor work practice? Was it caused by poor housekeeping practice; or, was it a child experimenting with fire? In any case if the cause has been determined that appliance or practice may be able to be changed or eliminated and the safety of the public assured.
  3. Statistics from cause determinations can assist with statistics on fire attendance and whether fire services have attended in sufficient time to have a direct effect on fire damage to properties involved, or whether there needs to be changes made to response times, practices or fire station locations. NB: If the information (cause of fire) is not correct – then statistics aren’t correct and improper procedures will be adopted!
  4. Investigations into origin and cause can lead to data that may assist with fire prevention measures such as building construction, building materials behaviour, exit signage placement and evacuation effectiveness, fire detection or protection appliance placement and legislation and community safety procedures.

Does your Fire Service have a dedicated Fire Investigation section, or do your field Officers/firefighters carry out this role? What training and/or qualifications do these people have to qualify them as fire investigators, do they hold qualifications recognised by any particular Standard or agency requirement?

The Standard recognised world-wide for Professional Fire Investigators is the National Fire Protection Association (NFPA) Standard “NFPA 1033 Professional Qualifications for Fire Investigator” (2014) this contains a description of the Job Performance Requirements (JPR’s) to be classified as a professional fire investigator. This Standard is recognised and recommended by organisations across the globe, such as the International Association of Arson investigators [IAAI] (in excess of 90 Chapters worldwide), the National Association of Fire Investigators [NAFI] (members in 42 countries), the Australasian Fire Authorities Council (AFAC) and many texts relating to fire investigation by internationally recognised authors.

The recognised educational document that assists with education to allow fire investigators to attain the JPR’s in NFPA 1033 is “NFPA 921 Guide for Fire and Explosion Investigation” (2014). This is a document that is continually updated and amended by a large committee composed of internationally recognised experts in the field of fire investigation, plus public input, and goes hand-in-hand with NFPA 1033 to teach fire investigators how the job should be done in an effective, efficient and professional manner.

A distinctive burn pattern from a liquid accelerant related fire.

A distinctive burn pattern from a liquid accelerant related fire.

Who needs convincing?

If I consider myself a competent and effective cause and origin investigator, then the first person I need to convince is MYSELF! If I am not convinced I have made the correct determination, I STOP, consider all the facts again, review the situation, consider the alternatives, and continue until I am convinced. The correct methodology to be used, according to NFPA 921, is the “Scientific Method” which is used in the physical sciences.

4.1* Nature of Fire Investigations. A fire or explosion investigation is a complex endeavor involving skill, technology, knowledge, and science. The compilation of factual data, as well as an analysis of those facts, should be accomplished objectively, truthfully, and without expectation bias, preconception, or prejudice. The basic methodology of the fire investigation should rely on the use of a systematic approach and attention to all relevant details. (NFPA 921. Ch.4.[2014])

If I can’t convince myself, I ADMIT that I do not know the cause of the fire. I do not assign a cause unless I believe in it thoroughly, and I have convinced myself. (If the assistance is available, I get a second opinion – from a source I can trust). There are four main fire cause classifications that should be used:

20.1 Classification of the Cause. Determining the cause of a fire and classifying the cause of the fire are two separate processes that should not be confused with each other. Classification of a fire cause may be used for assignment of responsibility, reporting purposes, or compilation of statistics. Different jurisdictions may have alternative definitions that should be applied as required. The cause of a fire may be classified as accidental, natural, incendiary, or undetermined. Use of the term suspicious is not an accurate description of a fire cause. (NFPA 921 Ch. 20. [2014])

If and when I should have to prove my theories in a court before a magistrate or judge and jury, if I’m not convinced that I am correct, then I will have a difficult time convincing anyone else that I have made the right decision.

There are two ways in which the courts consider a case proven, one is “ON THE BALANCE OF PROBABIILITIES” and the other “BEYOND REASONABLE DOUBT”. The latter is the greater proof and is used in criminal cases. To satisfy myself that I have made the right decision on a determination, I have to make the decision which classification of proof applies.

If I made decisions on cause and origin without due care for my responsibilities, then not only will my reputation and credibility suffer, but many others like court cases, insurances claims etc. will suffer as well.

Burn patterns assist with telling the story.

Burn patterns assist with telling the story.

The Approach – Open Mind/Preconceived Ideas?

The initial approach to the subject scene is the most critical stage. There should be no bias or preconceived ideas regarding cause.

Before you look at the scene, do you get as much information as you can about it: time of fire, FIRE stations attending, what they found, what they did, what answers they received to questions asked, what eyewitnesses saw, what the first fire Officers’ ideas are on the cause, what is the background of the occupants/owners and the behaviour/relationship pattern existing?

OR, do you look at the scene first, examine the physical evidence and make an initial decision, before soliciting the answers to all your questions?

I reiterate my opening statement “The initial approach to the subject scene, is the most critical stage”, but the most critical part is to make this initial approach “WITH AN OPEN MIND” on all the possibilities.


Before starting to excavate, poke around, or move anything, always make sure you have taken all of the commonsense safety precautions.

  1. Wear protective footwear – to guard against hot debris, nails in timber, sharp objects and/or hot water/chemicals.
  2. Wear a helmet – to guard against falling objects or cracking your head when inspecting under stairs, cupboards, etc.
  3. Use gloves – be careful of glass, hot objects, chemicals, syringes etc, which may be beneath the debris.
  4. Wear protective clothing – Turn out gear, overalls or similar to protect clothing from contamination, or ruin.
  5. Have a B.A. set available, or some form of breathing protection, and don’t be afraid to use it! When subject to fire, chemicals and other products give off toxic fumes. If you should turn over an item which has been fire affected (paint tins, jars, bottles, etc) there is every possibility that toxic fumes/vapours may rise and affect you. The result of your breathing these fumes can be, at worst, fatal. There are documented cases of fire investigators, succumbing to the affects of breathing fumes unearthed in their excavations, days after the fire.
  6. ELECTRICITY – “ALWAYS” make sure the electricity supply is isolated to the building or the particular part of the building in which you intend to work. Don’t take the word of anyone that it is disconnected, ALWAYS check yourself, for disconnection, or use a detector to make sure.

Always play safe, never compromise on safety. Compromise doesn’t pay the rent or feed the family.


In conclusion, the field of fire investigation or more succinctly, Origin and Cause determination, can be very rewarding. The rewards come from taking an awful mess where people ask “How can you tell what happened here, I can’t even tell what room this is?” and put the pieces of the jigsaw together. From the pieces you complete the puzzle and make a determination.

The rewards are the sense of accomplishment, satisfaction and the knowledge that you have done your very best, plus, hopefully made it safer for the public.

For more information, go to www.nfpa.org/AboutTheCodes.asp?DocNum=921


National Fire Protection Association. “NFPA 921 Guide for Fire and Explosion Investigation” (2014). NFPA USA.

National Fire Protection Association. “NFPA 1033 Qualifications for Professional Fire Investigator” (2014). NFPA USA.

Share With:
Rate This Article

Ross joined the New South Wales Fire Brigades in 1970 and retired as an Inspector in 2003, spending sixteen years in the Fire Investigation Unit. He teaches Fire Investigation degree courses at Charles Sturt University, and has done since 2002. He is a member of the IAAI, ANZFSS, NFPA and has taught extensively throughout Australia, New Zealand and overseas.

Subscribe to Asia Pacific Fire today for FREE!

Choose a Printed or Digital subscription to have full access to our website content.

Subscribe here for FREE

To dismiss this message please login here