Wildfire Origin and Cause Investigation - Part 1

As the spring fire season approaches, fire investigators across the country will be responding to wildfires to conduct origin and cause investigations. In many jurisdictions, investigators are assigned to a type of investigation that is unfamiliar. During...

  1. Protection: Fuels will be unburned on the non-origin side (as shown is Photo 2)
  2. Grass stems: Remains will appear different depending on fire travel
  3. Foliage freeze: Accurate indicator of wind direction only
  4. Degree of damage: The amount of fire-related damage to a combustible object (as shown in Photo 3)
  5. Depth of char: Color and size has no bearing on fire intensity
  6. Angle of char: Fire patterns will be foliage or trunks
  7. Spalling: Caused by the breakdown of the surface of rocks exposed to heat
  8. Curling: Leaves and vegetation will curl inwards towards source of heat
  9. Sooting: Occurs on the origin side of the fire
  10. Staining: Non-combustible objects effected on origin side of fire (as shown in photo 4)
  11. White ash: Product of complete combustion
  12. Cupping: Associated with small-diameter fuels
  13. V-patterns: The area of origin may near the point of V (best viewed from aircraft)
  14. Die-out patterns: Areas where fire died out on its own


The wildfire investigation is a challenge for any fire investigator. If you have the opportunity to assist with an investigation, you will be exposed to a different technique of interpreting fire patterns. Remember to work from the area of most intense burning, to the area of the least intense burning. Make sure to follow the burn-pattern indicators, as you may find multiple points of origin. Remember to take your time and do not rush the investigation by pre-judging the area of origin or cause of the fire. Become familiar with the fire-line handbook and ensure you follow the standard firefighting orders and watch out situations. Enroll in S-130/S-190 and FI-210. The educational experience is excellent and it will make you a better investigator.


  • NFPA 921, Guide for Fire and Explosion Investigations, 2008 ed. Quincy, MA: National Fire Protection Association, 2008. Print.
  • Wildfire Origin & Cause Determination Handbook, 2005 ed. National Wildfire Coordinating Group, 2005. Print.

ROBERT DISBROW JR. IAAI-CFI is a 22-year veteran of the fire service. Rob is a career firefighter/investigator with the City Of Bayonne, NJ, Fire Department and also conducts origin and cause investigations for a forensic engineering firm based in New Jersey. He is a life member of the Laurelton Fire Co. # 1 and a fire commissioner for the Howell Township Fire District # 1. Rob holds an associate degree in fire science and is a IAAI-CFI certified fire investigator and NAFI -CFEI certified fire and explosion investigator. He is also certified as a fire inspector, hazardous material specialist, fire instructor and juvenile firesetter intervention specialist and has been investigating fires for the past 15 years. View all of Rob's articles hereHe can be reached via e-mail at: disbrow282@hotmail.com.