Investigation Update: What Caused Colorado's Marshall Fire?

BOULDER, CO — The investigation into the possible causes of the Marshall Fire — which started on Dec. 30 — is nearing its conclusion, the Boulder County Sheriff's Office said in a news release.

Evidence and photos have been gathered, interviews conducted and information reviewed, the news release said.

Now that the physical aspects of the investigation are almost complete, the next step involves analyzing and reporting on that evidence, a process that, according to the news release, could take weeks or months.

Boulder officials said that they are investigating local coal mines, power lines and human activity to ascertain what might have caused what's been dubbed the most destructive fire in Colorado history.

The fire destroyed 991 structures and damaged 127, the sheriff's office said in a Jan. 1 news release.

As of Jan.3, the sheriff said in a news briefing that part of the investigation was focused around the area in which someone captured video of a burning shed on the day the fire started. He said then that the fire originated somewhere in the neighborhood of the shed in the video.

According to Boulder County's Office of Emergency Management, no downed powerlines were reported at the time of the fire.

Colorado has reported two fires in the last two decades that were caused by burning coal mines that spread to the surface. These fires, experts say, pose a significant threat, as they cannot be extinguished by "covering it up and trying to take away the oxygen," Jurgen Brune a Colorado School of Mines engineering professor said.

Coal fires are nearly impossible to predict and release toxic emissions, including mercury and carbon dioxide.

As of 2019, Colorado officials were monitoring nearly 40 underground coal fires.

"We know our community members want to know what happened and we are doing everything we can to make that happen. We will not be conducting media interviews or releasing more specific investigation details until the investigation is concluded," the release said. "Once this lengthy and important investigation is completed, that information will be shared with our community members and the media."

Reporting from the Associated Press was used in this report.