DENVER (KDVR) — The investigation into the cause of the Marshall Fire has concluded. Thursday morning, the Boulder County Sheriff’s Office will discuss the outcome of its search for the origin of the most destructive wildfire in Colorado history.

A news conference will be held at 10 a.m. Thursday. It will be covered live on FOX31 and

The sheriff’s office described the press conference as being about the “investigative outcome,” but did not share details on what could be revealed. Sheriff Curtis Johnson and District Attorney Michael Dougherty will be speaking, the sheriff’s office said.

Beginning on the morning of Dec. 30, 2021, the Marshall Fire destroyed 1,084 residential structures in Boulder County and an additional seven commercial structures. Two people were killed in the fire.

High wind fueled the flames to quickly spread. The city of Louisville, town of Superior and nearby portions of unincorporated Boulder County had the most significant damage.

Losses from the fire are estimated at more than $2 billion.

Homes burn as the Marshall Fire rips through a development in Superior, Colo. on Dec. 30, 2021,
Homes burn as the Marshall Fire rips through a development in Superior, Colo. on Dec. 30, 2021, (AP Photo/David Zalubowski)

What caused the Marshall Fire?

In Dec. 2022, one year after the fire, FOX31 talked with the thensheriff about his department’s investigation into the cause.

“I can tell you we have investigated every potential cause, and I think we have it narrowed down to probably a couple of potential causes of ignition,” former Boulder County Sheriff Joe Pelle said in the 2022 interview. Pelle retired in January and was succeeded by Curtis Johnson.

FOX31 asked about three potential causes, based on viewer videos, tips, as well as discussion and rumors within the community. Those were: a fire at the property owned by Twelve Tribes, downed Xcel Energy power lines, and the Marshall coal mine fires underground.

“We’re looking at all those things,” Pelle said in 2022.

At that time, Xcel Energy told FOX31 the power lines and equipment in question were thoroughly inspected and showed no signs it started the fire. Officials with Twelve Tribes had no comment when FOX31 asked about the fire seen on their property the day of the Marshall Fire.

A lawsuit has been filed against Xcel Energy alleging downed power lines near Eldorado Springs Drive and Foothills Highway may have caused the fire.

The lawsuit continues to move forward after a judge in November denied Xcel’s motion to dismiss the suit.