Kieren, 79, was pronounced dead at 12:50 a.m. at the Medical Center of the Rockies in Fort Collins, Colo.
Wyoming Highway Patrol said Samantha Brown, 25, had been driving east on Wyoming Highway 230 when saw Kieren's car parked on the side of the road and changed lanes to pass it. She said she did not see him standing on the road until she felt her car hit something.
The Albany County Attorney's Office will decide whether to file charges against Brown.
Celebrity Families of 2014 [PHOTOS]