DeKALB | Fire is one of humanity’s oldest tools and perhaps the hardest to control.

California authorities investigating an arson wildfire that killed four firefighters questioned two people Monday, while firefighters contained the blaze after five days, The Associated Press reported.

The recent California fires bring up questions of what steps are taken to determine if a fire is merely accidental, or if criminal intent is at work.

Where it started

Greg Hoyle, a DeKalb Fire Department captain, helps oversee the fire investigators that look at the cause of incidents.

“We investigate all fires in the city of DeKalb to determine their cause and origin,” Hoyle said.

Hoyle said the fire investigators approach every fire with the same investigative techniques, using their knowledge of how fires behave to determine where and how the fires began.

“We look at the big picture,” Hoyle said. “It all comes down to where the fire started. We look at the origin of the fire and eliminate potential causes.”

Firefighter Drew Wells is a 17-year veteran of the DeKalb Fire Department with four years of service as a fire investigator.

Wells said determining the origin of a fire requires investigation, interviewing people involved and cooperating with laboratories to conduct careful testing.

Wells used an example of a burned section of carpet as the origin for a fire.

Carpet many times contains hydrocarbons, the same sort of basic material found in accelerants that an arsonist could use. The presence of the hydrocarbons in the very material of the carpet might make determining whether an accelerant was used very difficult, Wells said.

“We’ll take another piece [of carpet] as a baseline sample, preferably one far away from the fire’s origin, and [the lab] will take a reading of the material and compare it to the sample,” Wells said.

The network of laboratories and fire investigators draws support from the Illinois State Fire Marshall’s office, and can determine a large number of details about a fire, Wells said.

Wells also said the Fire Marshall’s office employs, among other things, a K-9 unit with dogs trained to detect accelerants.

“We’ve got all kinds of tools at our disposal,” Wells said. “A dog’s nose is more sensitive than any testing process.”

Training and certification

DeKalb has 10 firefighters with state certification that can double as fire investigators, Hoyle said.

Wells said the difference between a fire investigator and an arson investigator is that arson investigators also possess arrest powers, making them peace officers with responsibilities similar to police officers.

“In a smaller town like this, it’s just not cost-effective,” Wells said.

DeKalb firefighters that are inducted into fire investigation go through three 40-hour courses at the Illinois Fire Service Institute at the University of Illinois, Wells said.

Maintaining a fire investigator’s certification requires on-the-job training as well as continuing education, Hoyle said.

The takedown

DeKalb’s fire investigators are not law enforcement officials, Hoyle said.

The fire department works with the DeKalb Police Department, should an investigation reveal that a fire had criminal origins.

Wells remembers one incident of arson in recent years that ended in the arrest of suspects after an investigation by the DeKalb Fire Department and cooperation with the police.

“When we proved that it couldn’t happen the way they said it did, they admitted to it,” Wells said. “Once they saw the evidence that was against them, they knew they didn’t have a chance.”

Wells said DeKalb has seen a small number of arson cases in past years, though there are two cases still under investigation.

Wells said the science of investigating fires continues to evolve.

“It is a science that is ongoing,” Wells said.