Boulder County, Colo. - The Boulder County Sheriff’s Office has concluded the investigation into the cause and origin of the Marshall Fire. During the last 18 months, the Sheriff’s Office focused on three possible causes of the December 30, 2021, Marshall Fire: a fire start located at 5325 Eldorado Springs Drive, arcing Xcel Energy powerlines, and underground coal mine seams.

Burn patterns, video footage, and satellite imagery show that the Marshall Fire was comprised of two fires that eventually merged becoming the Marshall Fire. Investigators worked to determine where the two original fires originated from. It was determined that one fire started on a residential property located at 5325 Eldorado Springs Drive where a legal burn had occurred the previous week and had been covered with dirt but had been re-ignited due to the high winds on December 30. The second fire was started by arcing powerlines located just south of the Marshall Mesa Trailhead, located southeast of the intersection of Highway 93 and Eldorado Springs Drive. Investigators found no evidence that elevated underground fire activity in the coal seams produced surface temperatures capable of starting a fire, although that cannot be completely ruled out.

Members of the Boulder County Sheriff’s Office conducted an extremely thorough investigation with assistance from the District Attorney, the United States Forest Service, the Colorado Department of Mining and Reclamation Services, the Colorado Bureau of Investigation, several local fire departments, an electrical engineer, and other experts. The District Attorney’s Office reviewed all the findings and considered possible criminal charges. Prosecutors may initiate and maintain criminal charges only if the charges are supported by probable cause and there is sufficient admissible evidence to support a conviction beyond a reasonable doubt.

Applying this standard, no criminal charges will be filed related to the ignition of the Marshall Fire. The decision of the District Attorney’s Office is consistent with the conclusion reached by the Sheriff’s Office. Though the fire devastated thousands of people, there is insufficient evidence that a crime was committed. If new information comes to light through other investigations or civil litigation, the Sheriff’s Office and District Attorney’s Office will review it.

The full investigative summary which goes into significantly more detail about the investigation and the decision making about criminal charges can be found here.

The press conference where the Sheriff and District Attorney reviewed the investigation and charging decisions will be posted in English or Spanish later today.

The associated Boulder County Sheriff's Office case number is: 21-6301.

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/s/ Carrie Haverfield, Public Information Specialist