Dawn Tollis has long been fascinated by fire. “It’s a thing that demands respect,” she says. “It is a living, breathing thing.”

As the only full-time investigator with Colorado Division of Fire Prevention and Control (DFPC), Tollis knows firsthand how powerful–and destructive–a single flame can be. In the past two years, Tollis has examined 110 fires across the Centennial State (this includes wildland, residential, and vehicle fires), spending countless hours connecting seemingly disparate threads of data in an effort to determine how blazes begin. “It’s so complicated,” she says of the process of scrutinizing burn patterns for clues. “There’s so much to try and look at and absorb and try to analyze properly.”

The Centennial State’s ability to investigate fires has come under scrutiny in recent months, as officials try to determine the cause of the Marshall Fire, which destroyed 1,089 homes in Boulder County. Historically, Colorado has been bad at pinpointing the cause of wildfires. According to an in-depth investigation by Colorado Public Radio (CPR) published in November 2021, our state ranks last among western states at solving large, human-started wildfires. Between 2000 and 2018, investigators determined the origin of just 43 percent of the state’s large wildfires. In response, state Democrats recently proposed legislation to bolster the work at DFPC, which currently has only six part-time investigators in addition to Tollis, the only full-time investigator.

“We are looking forward to working with the bill sponsors and hearing more about what they want to accomplish through DFPC,” Mike Morgan, DFPC director, told 5280 via emailed correspondence with a spokesperson.

In the meantime, to help better understand the process, we asked Tollis to break down how Colorado fires are investigated. (The DFPC declined to comment on the Marshall Fire, since it is still being investigated. As such, this article describes her general process.)

Once she’s called to an assignment, Tollis first tries to learn all she can about the incident. That includes details like precisely when flames broke out; what the weather conditions were at that time; how many people responded to the fire and what type of equipment they used to fight the flames; who was first on the scene and if they can describe exactly what they saw when they arrived; and if there are any other witnesses who may have valuable intel.

Then, once Tollis actually arrives on site, she does a full examination of the remaining evidence. This part of the process can become “extremely complicated,” Tollis says, depending on how much of the scene remains and what char markings investigators are able to read. These markings, which Tollis refers to as ”patterns,” can help indicate what direction the fire was burning.

Tollis, who has done more than 200 hours of training for her profession, examines lots of different objects for patterns–including rocks, concrete, wood, trees, grass, and building remains–and then tries to piece that information together alongside other clues. “The patterns almost talk to you,” she explains. “And I know it sounds totally corny, but if you can read the patterns, and you know how the fire was fought, and you can read airflow and direction and know which way the fire was moving, it will talk to you and almost tell you the path that it traveled.”

Fire investigator Dawn Tollis and her dog JoJo. Photo courtesy of Colorado’s Division of Fire Prevention and Control

Tollis also looks for any possible ignition sources that could have started the fire with the help of JoJo, a three-year-old service dog who can sniff out the presence of ignitable liquids. Throughout the process, Tollis takes photographs, handwrites observations in notebooks, and does online research to better understand what she’s seeing on scene.

Sometimes, though, there’s not much physical evidence to work with. And that’s where witness statements come in. Tollis asks witnesses a litany of questions, like: Where did you first see flames? Where did you first see smoke–was it up high or down low? Do you remember this window being intact? Was that door open or closed? Her goal is to get the best recollection possible, while also taking into account the fact that witnesses may have just experienced something traumatic. Video footage of the fire, if it exists, can also provide crucial information, says Tollis.

Some fire investigations are more complicated than others. Vehicle fires, in general, can be extremely tough because they occur in such a small area, says Tollis. And wildland fires, she adds, can be challenging because they are so uncontrolled. A torched multi-story condo could be more difficult than a single-family structure that’s burned. And a fire in a hoarder’s house would likely be more complicated than a home that doesn’t have as many combustibles inside. “The fire reacts different in the different environments,” explains Tollis. “So it’s reading a different book.”

Tollis can’t say how often she is able to determine the cause of a fire, but reiterates how complicated and challenging the process can be. “It’s a giant puzzle that you’re putting together. And you have to figure out, do these pieces fit or do they not?,” she says. “And hopefully, the pieces all come together, and you get a pretty good picture of what happened in that fire event. [That] doesn’t always happen.”

Per Colorado state statute, fire origin and cause investigations are the responsibility of local fire chiefs, and DFPC exists to support local jurisdictions. Oftentimes, that means Tollis is called in to help with the most complicated cases that local jurisdictions can’t solve on their own, says Chris Brunette, DFPC fire and life safety section chief.

As for Tollis, who has spent anywhere from eight to 80-plus hours on a single investigation, she realizes in the wake of a fire, people just want answers. But getting that clarity requires patience. “We want to exercise our due diligence and make sure that we get it right,” she says. “And sometimes, it takes a little bit of time.”

(Read more: Why Grassland Fires Still Surprise Us

Editor’s note 2/22/22: An earlier version of this article referred to the state’s only full-time fire investigator as Dawn Rooney. Her name is actually Dawn Tollis. We regret the error.