Shadow on the Ridge: Colorado’s First Mountain-Lion Killing in 28 Years

The Last Hike

At dawn last Saturday, 38-year-old wildlife biologist Luke Mercer laced his boots at the Raspberry Gulch trailhead, promised his wife he’d be home for lunch, and vanished into the pine-scented silence of the Rocky Mountains. By nightfall, a search dog found his body wedged beneath a fallen aspen, his orange day-pack shredded, his throat bearing the unmistakable signature of a cougar.

A Community Shaken

Colorado Parks & Wildlife confirmed Monday that DNA scraped from claw marks on Mercer’s jacket matches that of a 120-pound male lion tracked since 2021. If verified by the coroner, it will mark the state’s first fatal attack since 1997 and only the 24th recorded in North America in the past century.

‘We Thought We Knew This Cat’

“He was collared, he was shy, he kept to the elk herds—none of the usual red flags,” said CPW carnivore biologist Dr. Elena Vance, voice cracking over static on a satellite phone. “We monitor 190 lions across this range. This one never once came into town.”

The Deadly Encounter

Investigators reconstructed Mercer’s final hours through GPS pings on his smartwatch: a steady climb to 9,400 ft, a 20-minute stop near a waterfall—probably to shoot wildflower photos—then a sudden 300-yard sprint at 8:17 a.m. The watch’s heart-rate spiked to 187 bpm before going dark.

Signs at the scene tell the rest:

• Cougar tracks overlay Mercer’s boot prints—meaning it stalked, not ambushed.
• His bear spray was still holstered, safety clip on.
• A single set of lion tracks led away, suggesting the animal fed, then left.

Colorado’s Lion Quandary

The Centennial State’s cougar population has doubled since 2000, rebounding alongside booming deer and elk herds. Suburbs now push into foothills once ruled by apex predators, and sightings in Boulder and Denver suburbs have tripled in five years. Yet fatal attacks remained a Western myth—until now.

What Experts Want You to Know

• Make yourself big, loud, and back away slowly; running triggers chase instinct.
• Keep children within arm’s reach on trails; 64 % of attacks involve kids.
• Carry bear spray—works on lions if deployed before contact.

The Hunt—and the Debate

CPW set traps within hours; by Tuesday morning the suspect lion was euthanized and sent to a Fort Collins lab for rabies testing. Some neighbors want the entire pride relocated; others demand a limited hunt. Wildlife advocates warn knee-jerk killings could destabilize the ecosystem, forcing younger, inexperienced cats closer to people.

“One tragedy doesn’t erase decades of coexistence,” said Mercer’s colleague Dr. Marcus Thorne at a candlelight vigil Monday night. “Luke spent his life proving that predators and people can share these mountains. The best way to honor him is to keep proving it.”

A Final Footprint

On Tuesday afternoon, park officials reopened Raspberry Gulch with new warning signs. At the trailhead, someone tucked a laminated photo of Mercer into a split-rail fence. Scrawled beneath: “Stay curious. Stay loud. Come home safe.”