By afternoon, however, the protocol in Elisa's patrol started to unravel. DeHoff, for his part, said he noticed nothing amiss when he passed by the group on his way up canyon. There were two girls remaining of the original four—Elisa and Karen—and four impatient boys. After DeHoff had passed, Elisa at one point started weeping, according to Karen, the only member of the group Elisa's family has been able to contact.

The Needles ranger station in nearby Canyonlands National Park marked a temperature of 104ºF (40ºC) that afternoon. In the furnace effect of the canyon, the temperature was likely closer to 110ºF (43ºC). The effort to walk under the roaring sun was apparently too much for Elisa. She'd eaten almost nothing all day. She asked to take a rest break. She then requested another. It was late afternoon, the crest of the day's heat. There were one and a quarter miles (two kilometers) to the respite at the river.

The four boys later told Outward Bound investigators that a group decision was made at 4:45—the patrol would disband. The boys headed out and left the two girls to be swept up by Alex in the rear.

Elisa and Karen proceeded for a short while. Then the story clouds up. According to Karen, who was the last person to see her alive, Elisa now opted to strike out down canyon alone. Alex says she found Karen around 5:15 p.m., wandering down the middle of the jeep road.

As for Elisa, we can only guess what happened. We know that she had enough food with her and that she started the day with two bottles of water. What is most perplexing is the route she chose after she left Karen. She abandoned the jeep road altogether and walked a quarter mile south into a side canyon. Was she lost? The jeep road and drainage is clearly blazed at that point in the canyon. Had she lost her ability to reason? Heat exhaustion can lead to disorientation; heatstroke guarantees it. Both conditions result from a rise in the body's core temperature, and both can strike even if a hiker is hydrated, though heatstroke is deadly. Elisa walked up the side canyon with its weird mudstone walls, the rocks too hot to touch. Then she fell to her knees and pitched forward onto her face. A trickle of blood ran from her mouth. There she died, probably within minutes. The medical examiner later ruled "probable heatstroke" as the cause of death.