DENVER (KDVR) — The cause of Colorado’s most destructive wildfire was determined to be two separate fires that combined to make the Marshall Fire, Boulder County Sheriff Curtis Johnson said Thursday.

The first fire sparked around 11 a.m. at a residential property located at 5325 Eldorado Springs Drive, Johnson said. The residents had conducted a controlled burn of brush on Dec. 24, 2021, and buried the fire after it was done. Firefighters checked that fire on that day and determined it was extinguished properly.

Johnson said high winds on Dec. 30 blew up the buried embers which caught oxygen and re-sparked. It was determined that smoldering combustion can happen weeks and even months after being buried, Johnson said.

A second fire, 2,000 feet from the first fire, was most likely caused by discharged particles from an Xcel Energy power line, Johnson said. That fire sparked at the South Marshall Mesa Trailhead.

At some point, the two fires met to become one which resulted in the Marshall Fire, Johnson said. The exact location of their combination could not be determined.

At the conclusion of the investigation, the district attorney’s office decided there will be no charges filed for the cause of the fire. There is no evidence a crime was committed, District Attorney Michael Dougherty said in a press conference Thursday.

Marshall Fire investigation

Over the past 18 months, FOX31 has asked the sheriff’s office about three potential causes based on viewer videos, tips, discussion and rumors within the community. Those include a fire at the property owned by Twelve Tribesdowned Xcel Energy power lines, and the Marshall coal mine fires underground.

Those who were impacted by the fire anxiously awaited the announcement.

“It’s mixed feelings because it won’t change what happened, but maybe it’ll bring closure to understand what happened,” said Jessica Carson, whose home burned down in the Marshall Fire on Dec. 30, 2021.

Two people were killed in the blaze, and more than 1,084 residential buildings were destroyed as high winds caused the flames to spread through Louisville, Superior and unincorporated parts of Boulder County.

In all, losses from the fire are estimated to have cost more than $2 billion.