FOX31 Denver

Marshall Fire investigation probes coal mines, power lines, human activity

Nick Wills

FILE - Rowdy Alexander watches from atop his horse as a hillside burns on the Northern Cheyenne Indian Reservation on Aug 11, 2021, near Lame Deer, Mont. An area outside Denver where Colorado's most destructive in history wildfire burned 1,000 homes last month is home to numerous abandoned coal mines that authorities say could be a potential cause of the wind-driven wildfire. This past summer in Montana, smoldering coal seams were blamed for a string of major fires that burned hundreds of square miles and prompted widespread evacuations. (AP Photo/Matthew Brown, File)

BOULDER COUNTY, Colo. (KDVR) — Despite being incomplete, an update has been released by those leading the investigation into what caused the most damaging fire Boulder County has ever seen.

As calls rise from the victims of the Marshall Fire demanding that local governments speed up the rebuilding process, officials at the Boulder Country Sheriff’s Office have offered up an update on the status of their ongoing probe into the origin of the blaze that ignited one month ago.

According to the statement released on Monday morning by the BCSO, most of the “initial investigative work” into what or who caused the disastrous fire, is nearing completion. This process includes photo gathering, video reviewing, interviewing and general evidence gathering.

Once this portion of the investigation is completed, the 20th Judicial District Attorney’s Office, which has been engaged since the beginning of the process, will decide alongside the Sheriff’s Office whether or not to press charges.

Potential origins of the Marshall Fire

The potential causes cited in the sheriff’s statement include nearby coal mine fires, downed power lines and human activity, although these are not the only theories being looked into.

A pair of Boulder-adjacent underground coal fields that fall within the burn scar of the Marshall Fire have been smoldering since 1883. At the time, the two Colorado mines, the Marshall Mine and the Lewis Mine, were deemed by the state’s first mining inspector as “impossible to extinguish,” according to the Associated Press.

Reports obtained by the FOX31 Problem Solvers show that around noon on Dec. 24, 911 dispatch received “the report of a trash or grass fire as seen from a passer-by driving on Highway 93.” The Twelve Tribes property along this strecth of road has had a history of controlled burns.

“I really don’t know where it started. I know for sure I saw smoke there at 11:10 when I was driving by,” said Anne Michaels, the woman who reportedly filmed the smoke rising from the backyard of the Twelve Tribe property and knocked on doors to warn neighbors.

Downed power lines have also been mentioned as a potential source of the fire, but Xcel energy declared on Dec. 31 that they found no evidence linking disabled cables as the cause of the disaster.