Investigating Cold Fires – Expert Article on Interpreting Evidence

To the uninitiated a fire scene looks like char and ash with no discernible evidence as to where or why a fire started. Short of finding a melted lighter or remnant of a match, most laypeople are unable to make any sense of the plethora of evidence surrounding them.

In this short article, fire investigator and retired fire fighter, Timothy Wilhelm interprets the evidence left at the scene of a fire. Through his trained eye, he provides valuable insight into how experienced fire investigators can interpret the soot and ashes to determine origin and cause.

Investigating Cold Fires

Investigating Fires: First at the Scene

In the years I spent as a fire investigator for the City of Erie, life was great. Being at the scene while the fire was in progress was a tremendous advantage in determining the Origin and Cause of a fire.

Many times I would respond to a call and arrive before the fire engines. I could observe the fire dynamics in force as the fire progressed. I could also witness the fire department operations and how ventilation affected fire movement. This experience was crucial in my professional development, providing valuable hands-on training upon which my opinions are based in the course of my forensic investigations.

The progression and extinguishment of a fire leaves observable and identifiable patterns. The ability to recognize and identify these patterns is paramount to one’s success as a fire investigator.

Investigating Fires: Last at the Scene

In my years as a fire investigator with Robson Forensic, life is still great, but professionally more challenging. Rather than arriving first at the scene, I am frequently introduced to a fire scene years after the actual incident. Rather than watching the development and extinguishment of the fire, I am provided with a banker’s box of grainy photos, a fractured and sometimes incomplete fire report, and evidence that is no longer available.

Despite the challenges, there is still much information to be gleaned from the available materials. Below we present two images: the first is an example of a typical evidence photo that is available for review; the second is an identical photo with mark-ups to identify the evidentiary clues that help to decipher the scene. I challenge you to focus on the first image and draw your own conclusions before moving on to the next.

To the trained eye, there is an incredible amount of information in this photograph that is useful toward determining origin and cause. What conclusions are you able to make? See the image below for help.

As mentioned earlier, the progression and extinguishment of a fire leaves observable and identifiable patterns. A description of each of the numbered items is below:

  1. V-pattern on the backsplash
  2. Movement pattern on the front of the microwave
  3. Heavy oxidation on the side of the microwave
  4. Heavy oxidation / no handle on the pan
  5. V-pattern on the back splash behind the stove.
  6. Clean burn on the wall behind the stove.

Based on this one photo you can determine the fire originated on the right side of the microwave.

  • Pattern #1 was caused by a secondary fuel source
  • Pattern #2 tells us the fire was moving from the right to the left
  • Pattern #3 tells us the fire was more intense on the right side than on the front of the microwave.
  • Pattern #4 tells us the pan was subjected to intense heat
  • Pattern #5 was caused by the fire extending from the rear of the stove top
  • Pattern #6 was caused by the fire burning the soot off the drywall leaving a clean area

Although the cause of the fire cannot be determined from this photo alone, it is enough to eliminate other ignition sources outside the area of origin.

Thankfully I have decades of training, education, and hands-on fire investigation experience to assist in guiding my opinions. I invite you to contact me directly to discuss any fire incidents you are currently concerned with, and how I or another fire investigator at Robson Forensic can assist.


Our Fire and Explosion practice provides origin and cause investigations, reporting, and testimony suited to the size of the loss and your budget. The group includes certified fire and explosion investigators; electrical and mechanical engineers; architects, product engineers, materials scientists, and other specialists.

For more information, visit our Fire Investigations practice page