Ian O'Brien trekked for more than four hours through Colorado's San Juan mountains with one goal in mind — reaching the top of Hesperus Mountain.
When he finally did, he took a selfie and sent it to his girlfriend, Beth.
That was the last time she or any of his family heard from him.
The 28-year-old suffers from epilepsy, meaning he's prone to seizures. His loved ones fear he might have had one and didn't have his medicine with him.
He had a fully-charged phone and Garmin watch with GPS enabled, but his family has been unable to reach him.
By 11.30pm on Saturday, the day he went missing, his family launched a search-and-rescue mission to try and find him, filing a missing persons report with the Cortez Police Department.
O'Brien had started his hike around 2 p.m., then reached the summit of Hesperus at around 6:30 p.m., which is when he texted Beth.
His sister Kelsey O'Brien Rodriguez told The Arizona Republic that her brother was reportedly seen the following day looking "disoriented" as he walked into the nearby woods.
But Montezuma County Sheriff Steve Nowlin said the sighting likely wasn't of O'Brien — the man hikers saw was reportedly wearing different clothing.
When he went missing, O'Brien had been wearing a gray tank top, black shorts, tennis shoes and possibly had a gray long-sleeve hiking shirt, Rodriguez said.
As of Wednesday afternoon, there havn't been any additional sightings of O'Brien, and his condition is currently unknown.
But Rodriguez is confident in her brother's survival abilities — this isn't the first time the 28-year-old has gone hiking on the trails in the Echo Basin.
"He's an extensive, experienced outdoor hiker and knows the area extremely well," she said. "He went out on a hike by himself at a reasonable time, to a hike he'd done before."
His other sister, Molly, agreed.
"Ian has an extensive background in survival in the wilderness," she told KDVR. "If anyone could survive in the wilderness, it would be him, like 100% by himself."
That doesn't necessarily mean he'll make it out alright, however.
"The added component of not having his medication means that he’s likely having multiple seizures and being postictal [a post-seizure state] while in the woods and could be in a lot of danger right now," Molly said.
The family is encouraging experienced hikers to venture out to the area where Ian was last seen and join the search efforts.
As time wears on, however, his prospects weaken.
If anyone has any information about the lost hiker, they are encouraged to contact La Plata Search and Rescue at 970-385-2900.
