LA PLATA COUNTY, Colo. (KDVR) — Molly and Kelsey O’Brien spent Tuesday coordinating with search and rescue teams from their family’s home in upstate New York as crews continue to search for their brother Ian, who’s lost in the San Juan mountains of Colorado.

Ian O’Brien was last seen on Saturday, June 24, after summiting Hesperus Mountain northeast of Durango. According to his sisters, O’Brien texted his partner that he summited the mountain after 6 p.m. as he was coming back down.

Despite having a Garmin inReach satellite device and a fully charged phone, the family has not been able to make contact. They filed a missing persons report with the Cortez Police Department, and Montezuma Search and Rescue has been involved in the search since late Saturday night.

Epilepsy big worry in search for missing Colorado hiker

The biggest concern for his sisters is O’Brien’s medical condition: epilepsy. While he carried medication in his backpack, it is unclear if he still has access to the medication in the wild.

“Ian has an extensive background in survival in the wilderness. That’s if anyone could survive in the wilderness, it would be him, like 100% by himself,” Molly O’Brien said. “But 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.”

Kelsey O’Brien indicated there was a reported sighting of their brother on Sunday, and witnesses may have seen him far from the trail without a backpack in the La Plata Canyon area.

“He’s everybody’s favorite. And he’s just, he’s wonderful. You know, we don’t see him a lot because he lives on the West Coast, but when he comes, he’s in the snow rolling around, pulling the sled, letting the baby pull his beard, wrestling with the dog. He is, he’s just so much joy,” Kelsey O’Brien said.

Anyone with information that could help search and rescue teams can call La Plata Search and Rescue at 970-385-2900.