Boulder County Sheriff Curtis Johnson (right) speaks during a press conference on the investigative outcome into the cause and origin of the 2021 Marshall Fire, at the Boulder County Sheriff’s Office in Boulder, Colorado. Associated Press

Jesse Bedayn, Colleen Slevin and Mead Gruver, Associated Press

Embers from a smoldering scrap wood fire set days earlier outside a home used by a Christian religious communal group along with a sparking power line caused a 2021 Colorado wildfire fanned by high winds that destroyed nearly 1,100 homes and left two people dead, authorities said on Thursday. Authorities spent 18 months investigating and determined criminal charges were not warranted for either The Twelve Tribes that occupied the home or the utility in charge of the power line, Boulder County District Attorney Michael Dougherty said at a news conference. “If we were to tell you today we are filing charges, it would be wrong and unethical,” Dougherty said.

The Dec. 30, 2021, blaze in heavily populated suburbs between Denver and Boulder caused $2 billion in damage, making it the most destructive in Colorado history. Two people were also found dead after what was known as the Marshall Fire. The inferno erupted following months of drought amid a winter nearly devoid of snow and fed on bone-dry grassland surrounding fast-growing development in the area near the Rocky Mountain foothills. It spread rapidly in winds that gusted up to 100 mph (160 kph) in places. For one woman who lost her home and watched the news conference, seeing photos and hearing about the fire all over again was almost as difficult as the fire’s immediate aftermath. “On top of trying figure out how it started, all this just stirs up all the same emotions. It makes you nauseous in re-remembering everything,” Barba Hickman said. Experts say similar events will become more common as climate change warms the planet and suburbs grow in fire-prone areas.

The scrap wood fire — buried by residents Dec. 24 in a manner approved by firefighters who stopped by that day to investigate — was one cause when the powerful winds uncovered the buried embers six days later, Sheriff Curtis Johnson said at the news conference. “Once they realised there was a fire and it was spreading, they attempted to put it out, but the winds were quickly spreading the flames faster than they could put it out,” said Johnson, who lost his home in the blaze and teared up during the news conference. A loose Xcel Energy power line caused a separate fire less than half a mile (1 kilometer) away around the same time, Johnson said. The two fires combined to cause the massively destructive blaze. Xcel Energy strongly objected to the findings of the investigation, contending in a statement that it didn’t have a chance to review what the company called “flawed” analyses.

“We strongly disagree with any suggestion that Xcel Energy’s power lines caused the second ignition,” said a statement from spokesman Tyler Bryant. “We operate and maintain our electric system consistent with leading energy service practices.” A worker at a Boulder deli run by The Twelve Tribes declined to comment or give their name on Thursday when The Associated Press visited the restaurant. Members of the group - a Christian religious community thought to have 2,000 to 3,000 members worldwide - have repeatedly declined to discuss the fire or what happened since the 2021 blaze. The fire that destroyed swaths of houses in the cities of Superior and Louisville, neighboring towns about 20 miles (32 kilometers) northwest of Denver, is blamed for the death of a 69-year-old man who lived near where investigators believed the fire started. The remains of a 91-year-old woman, who was last seen trying to rescue her dogs from her home in Superior, were also found.

Thousands of residents were at home the day before New Year’s Eve and used the suburban area’s extensive road network to escape amid smoke, flames and blowing embers, which spread the fire in the wind. Shifting winds caused the skies to turn from clear to smoky and then back again in an area filled with middle- and upper-middle class subdivisions surrounded by shopping centers, parks and schools. As smoke filled the parking lot of a Costco warehouse store and debris whirled around, a sheriff’s deputy ordered people inside to leave their carts, evacuate the sprawling building and head toward Denver, away from the fire. Within hours, it destroyed 1,084 homes and seven commercial buildings, and damaged nearly 200 structures. Old coal mines that smoldered underground in the area could not be ruled out as playing a role in the fire, but were not deemed to be part of the cause, investigators said.

The area includes an abandoned coal field where two underground fires, fueled by coal deposits, have slowly burned over the years. The fire, which spanned 9.4 square miles (24 square kilometers), ranks as the most destructive in state history in terms of homes and other structures destroyed and damaged. The second-most destructive fire erupted in 2013 outside Colorado Springs, destroying 489 homes and killing two. A lawsuit filed against Colorado’s largest utility, Minneapolis-based Xcel Energy, alleged that sparks from a power line started the blaze. It says witnesses saw a fire igniting near a power line in the area identified by investigators, with one witness videoing sparks flying from a malfunctioning power line and igniting a fire on the ground. Hickman’s husband expressed frustration the fire’s cause wasn’t pinned down more definitively.

“It doesn’t really provide any answers that help us. I guess I don’t know, it kind of leaves it open in my mind,” Rex Hickman said. The Hickmans said they might be interested in joining litigation against Xcel Energy to try to recover costs, pointing to a California utility’s 2019 settlement for wildfire damages. For now, the Hickmans have been settling into their new home in Charlottesville, Virginia, where they built a new home using insurance money. They plan to sell their vacant lot in Colorado. “We were looking to get away from the fires in the West, and I have asthma pretty badly. The constant fires every summer is one of the reasons for us moving on,” Barba Hickman said. The investigation took a long time for what was announced, but the decision not to pursue criminal charges seems appropriate, said Barney Thinnes, another homeowner who has had to rebuild. “I’m with the sheriff. I just want to move forward with the whole thing,” Thinnes said.