Officials say two mountain lions were euthanized and will undergo necropsies as part of the investigation.
GLEN HAVEN, CO — A woman died Thursday on the Crosier Mountain trail in unincorporated Larimer County after two hikers saw a mountain lion near her body and drove it off by throwing rocks, authorities said. The witnesses checked for a pulse around 12:15 p.m. and found none, prompting a large search for lions in the rugged forest south of this small community.
The death is Colorado’s first suspected fatal mountain lion attack since 1999 and has drawn state wildlife officers, sheriff’s deputies and local firefighters into a joint investigation. Officials say evidence at the scene was consistent with an attack, but the Larimer County coroner will determine the cause and manner of death and release the woman’s identity. Colorado Parks and Wildlife confirmed two lions located near the scene were euthanized later Thursday. Samples and full examinations are pending as authorities work to confirm whether one or more animals were involved and whether disease played any role.
Authorities said the hikers were about 100 yards away when they first spotted the lion near the woman on a remote stretch of the Crosier Mountain trail, which winds through steep, wooded terrain northeast of Estes Park. As they approached, they threw rocks and the cat retreated long enough for the pair — one of them a physician — to reach the victim and attempt to assess her condition. “This is a very common time of year to take mountain lion sightings and reports, especially in Larimer County, where this is very good mountain lion habitat,” Colorado Parks and Wildlife spokesperson Kara Van Hoose said. She added that the terrain is heavily timbered with sharp elevation changes and few clear lines of sight.
By late afternoon, state wildlife officers — aided by a CPW biologist already in the air on a deer survey — coordinated with Larimer County deputies, Estes Park police, Glen Haven Area Volunteer Firefighters and licensed houndsmen to track lions in the area. Officers found one lion at the scene and shot it as it fled; the animal was later tracked and euthanized. A second lion located nearby was also euthanized. Investigators say it remains unknown whether a single cat attacked the woman or whether more than one lion was involved. Pathologists will conduct necropsies and test for abnormalities and neurological diseases, including rabies and avian influenza. Officials said the victim appeared to be hiking alone, and they have not publicly released her name pending notification by the coroner.
The Crosier Mountain trail sits in the Arapaho and Roosevelt National Forests, about seven miles northeast of Estes Park and roughly 20 miles west of Fort Collins. The area is prime habitat for deer and elk in winter, which can draw lions to lower elevations and closer to popular trails. Sightings are common in Larimer County, but attacks remain rare. State records list 28 lion attacks on people in Colorado since 1990, with the last fatality in 1999. In recent weeks, hikers have reported close encounters on the same trail system, including a November incident in which a runner said he fended off a lion by striking it with a stick. Wildlife managers say that while lions can weigh up to 130 pounds and stretch more than six feet, they typically avoid people unless surprised, habituated to human areas or defending a kill.
The investigation now turns on two tracks: forensic exams of the euthanized lions and the coroner’s autopsy. CPW pathologists will look for injuries, body condition and signs of disease, and they will analyze stomach contents and collect DNA. Any match to hair, saliva or other material recovered from the scene could link a specific lion to the attack. The Larimer County Coroner’s Office will determine the woman’s cause and manner of death and is expected to release her identity after next of kin are notified. Agencies said additional field checks and patrols are underway through the first full week of January. Officials said they would decide whether to continue aerial searches in the surrounding drainages if new sightings emerge or if necropsy results suggest another lion was involved.
On Friday and Saturday, hikers described a quiet mood on the trailheads near Glen Haven. The small volunteer fire station’s bay doors were closed, and a few cars lingered at the base of the mountain roads as wind rattled lodgepole pines along County Road 43. “People who live up here know the lions are around,” said Lindsey Jones, who walked a short spur trail with her partner a few weeks ago after they said a cat shadowed them from a stand of aspens. “We left when it stared us down for too long,” Jones said. At a coffee shop in Estes Park, longtime resident Mark Dieffenbach said the community was waiting for answers. “Everybody’s talking about who she was and what exactly happened. We just want to know,” he said.
As of Sunday, state officials said necropsy testing on the two euthanized lions is pending and that the coroner will release the victim’s name and autopsy findings when complete. Agencies plan to provide an update early this week if lab results or new field observations change the risk assessment for nearby trails.
Author note: Last updated January 4, 2026.