Colorado Parks and Wildlife is investigating a suspected fatal mountain lion attack on the Crosier Mountain trail in unincorporated Larimer County, the agency announced January 1, 2026. If confirmed, the attack would be the first fatal mountain lion encounter in Colorado in more than 26 years—and the fourth in Larimer County’s recorded history.
Around 12:15 p.m. on New Year’s Day, hikers on the trail reported seeing a mountain lion near a person lying on the ground from approximately 100 yards away. As they approached, the witnesses scared the lion from the area by throwing rocks at the animal. One of the hikers, a physician, attended to the adult woman victim but did not find a pulse. CPW believes the woman was hiking alone.
CPW officers, Larimer County Sheriff deputies, Estes Park police, and Glen Haven Area Volunteer firefighters responded to launch an extensive search for mountain lions. A CPW biologist conducting aerial deer surveys in the county assisted in spotting and personnel transportation. Houndsmen used dogs to track the scent of lions.
Officers located one lion at the scene, shot the animal, and it ran from the area. Officers tracked the mountain lion and euthanized it. A short time later, a second mountain lion was found nearby and also euthanized. According to CPW policy, wildlife involved in attacks on humans must be euthanized to ensure public safety. It remains unknown whether one or multiple animals were involved in the suspected attack.
CPW pathologists will perform necropsies on the animals, checking for abnormalities and neurological diseases including rabies and avian influenza. The lions will also be tested for human DNA to confirm whether they were responsible for the attack. If the tested animals show no evidence of human DNA, CPW has indicated the search will continue.
The Larimer County Coroner will release the identity of the victim and cause of death.
All three Crosier Mountain trailheads—Glen Haven, Rainbow, and Garden Gate—were closed following the attack. Glen Haven sits approximately seven miles northeast of Estes Park, the gateway to Rocky Mountain National Park.
Warning signs preceded the attack. Glen Haven resident Gary Messina, a trail runner, told CBS Colorado he had a frightening encounter with a mountain lion on the same trail just over a month ago. The lion ran toward him as he jogged at daybreak. In the last six months, mountain lions have been blamed for several pet deaths around Boulder, Erie, and Fort Collins.
Larimer County has emerged as Colorado’s deadliest ground for mountain lion encounters. The state’s last confirmed fatal attack was October 2, 1999, when three-year-old Jaryd Atadero went missing during a church group hike on the Big South Trail in the Poudre Canyon—also in Larimer County. His remains were discovered in 2003, and the coroner listed the cause of death as a probable mountain lion attack. In 1997, ten-year-old Mark Miedema was killed by a mountain lion and dragged away while hiking with family in Rocky Mountain National Park. The state’s first recorded fatal attack occurred in 1991, when 18-year-old Scott Lancaster was killed while jogging near his high school in Idaho Springs.
Recent non-fatal attacks underscore the pattern. In February 2019, Fort Collins runner Travis Kauffman survived an attack at Horsetooth Mountain Open Space by suffocating a juvenile mountain lion with his bare hands during a ten-minute struggle. In March 2020, a rabid 91-pound mountain lion attacked two people west of Loveland—including Larimer County Sheriff’s Deputy Michelle Ross, who was bitten on the shoulder while responding to the scene. A UPS driver saved the first victim by beating the lion with a pallet.
CPW estimates Colorado’s mountain lion population at 3,800 to 4,400 animals—among the highest densities in the western United States. The agency classifies the population as “strong and abundant.” In November 2024, Colorado voters rejected Proposition 127, which would have banned mountain lion and bobcat hunting, by a margin of 55.5% to 44.5%. Hunters kill an average of 505 mountain lions annually in Colorado.
Mountain lion attacks on humans remain statistically rare, with 28 previous attacks reported to CPW since 1990. Studies estimate four to six mountain lion attacks occur annually across all of North America, with fatal attacks averaging fewer than one per year.
CPW spokesperson Kara Van Hoose said at a press conference that hikers and outdoor enthusiasts along the Front Range and Larimer County should expect to encounter wildlife. Mountain lions become more visible in winter as they follow deer and elk to lower elevations. The agency advises that if lions are spotted, people should make noise to scare them from the area, hold objects overhead to appear bigger, and back away slowly. Pets should be kept on-leash and not allowed to interact with wildlife.
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