The woman was discovered on Jan. 1 when two hikers came upon a mountain lion lying partially over her body on the Larimer County hiking trail, Colorado Parks and Wildlife said.
The death is considered a suspected mountain lion attack pending a report by the coroner's office, agency spokesperson Kara Van Hoose told the Coloradoan, part of the USA TODAY Network.
Van Hoose said the suspected attack happened at about 12:15 p.m. on the Crosier Mountain Trail, just south of Glen Haven. The trail is about 70 miles northwest of Denver.
Two men, one a physician, saw the mountain lion lying over the woman from about 100 yards away, Van Hoose said. They threw rocks at the animal as they approached and the mountain lion was scared away.
"It was acting protecitvely over the person when the two men saw it," Van Hoose said.
The physician said he did not find a pulse, according to Van Hoose.
VanHoose said an extensive search for the lion was led by Colorado Parks and Wildlife and other agencies. Searchers were helped by helicopters and houndsmen to track lions in the area. One was found, and an officer shot it, but it ran away. It was tracked and euthanized.
A second lion was found in the area and it also was euthanized, said Van Hoose, who added agency policy calls for euthanizing wildlife involved in human attacks. She said the agency will conduct necropsies on the two sub-adult to adult mountain lions checking for abnormalities and neurological diseases like rabies and avian influenza.
How rare are fatal mountain lion attacks?
Prior to this incident, there have been 28 mountain lion attacks of humans in Colorado, including three that were fatal, Van Hoose said. The last attack happened in 2023 near Buena Vista, over 175 miles away.
The state's last fatal mountain lion attack was on Oct. 2, 1999, when 3-year-old Jaryd Atadero went missing while hiking with a group on the Big South Trail in the Roosevelt National Forest of Larimer County. His body was discovered by two Fort Collins hikers near where he was last seen June 4, 2003. The case resulted in extensive national and international media coverage.
If proven to be a mountain lion attack, it will be the fifth in Larimer County and third since 2019.
In March 2020, a rabid mountain lion attacked two people, including a sheriff's deputy, west of Loveland. That mountain lion was found at a nearby home and shot by Colorado Parks and Wildlife officers about an hour after the attack. In February 2019, a local runner was attacked by a young mountain lion while running on ice-covered trails west of Fort Collins. The man fought and killed the mountain lion during the attack.
According to the nonprofit Mountain Lion Foundation, there have been roughly 30 reported fatal mountain lion attacks in North America since 1868. A 2011 study found mountain lion attacks are relatively rare, with about four to six per year in the United States and Canada. In 2025, a 4-year-old in Washington state was bitten by a mountain lion and an 11-year-old was attacked and bitten by one outside her Malibu, California, home. In 2024, California saw its first fatal mountain lion attack in 20 years when a man was killed and his brother was injured.
Colorado has a healthy mountain lion population, estimated at 3,800 to 4,400 adult lions, according to the Colorado Parks and Wildlife. In 2024, Colorado voters defeated Proposition 127, a ballot initiative to ban mountain lion hunting, by a 55% to 45% margin.
Good on the wildlife officials for finding the two cougars and putting them down.
We cannot have them knowing that they can kill people.