Toshiaki Amimoto, 65, and Etoko Amimoto, 60, were walking along a steep slope near Delicate Arch when they fell on Nov. 29 around 7:45 a.m., according to the Grand County Sheriff's Office.
A 30-year-old family member who was walking with the pair also fell and was flown to a nearby hospital with serious injuries.
The sheriff's office is investigating the circumstances surrounding the fall, but officials said there was some intermittent rain and snow in the area at the time.
The Associated Press contributed to this report.