Caleb, 23, a student home for the holidays, had always been curious about the case. His police officer father had been involved in the manhunt in 2010 so the Shumway brothers knew all about how Arellano seemed to disappear into the park's craggy landscape.
Still, Caleb Shumway believed he could locate Arellano. The Eagle Scout had grown up exploring the area's caves and crevasses, and he'd talked with his father enough to get a good idea of where Arellano may have hidden. He recruited his 15-year-old brother, Jarom, and they set out in search of clues.
The brothers were prepared to dedicate their entire break to the mystery - it had, after all, eluded scores of professional investigators. But they only needed 48 hours.
On their second day of searching, Caleb Shumway told the Salt Lake Tribune, the brothers slipped through a narrow opening into a small, cramped cave. Just near the cavern's mouth lay a bag containing a handgun and magazine and a single human bone.
It's really exciting finding some closure for all the families involved, all the police involved, and then just getting to be in the middle of it.
The brothers took some photos, then hopped out of the cave and hurried to tell the police. They met with law enforcement on December 24, who returned to the cave for a more thorough search. Even deeper into the void in the rocks, they discovered another backpack, a gun, clothing and a skeleton.
Police believe that skeleton belongs to Arellano. The remains have been sent to the Utah State Medical Examiner's office for identification, according to a Sheriff's Office press release.
Shumway hopes that his hunch was correct - the promised US$30,000 FBI reward is "pretty appealing" to "a poor college student", he told the Salt Lake Tribune, and it's one of the main reasons he started his search.
But he also hopes to provide some closure to Young, the park ranger who was shot by Arellano five years ago. Then 34, the ranger had pulled over at a dark trailhead to talk with a man in a parked vehicle to tell him he was camping illegally.
When he asked Arellano who he was, the man responded with a fake name and birth date, according to the Tribune.
Young turned toward his truck to check the information, and was shot in the back nine times. He fired back, then crawled 10m to his car to summon help.
"It's really exciting finding some closure for all the families involved, all the police involved, and then just getting to be in the middle of it," Shumway told KSTU. "It's exciting, and it feels good."
- Bloomberg