On Sunday afternoon Miller, 29, was discovered in the van in which he lived by a friend, who notified police. The Mono County Sheriff's Office confirmed the death Monday, saying the cause of death is unknown, pending autopsy, but foul play is not suspected.
Miller had a history of seizures after a 2005 motorcycle accident left him in a coma for 11 days. He recently took steps to qualify for the U.S. Olympics team in snowboardcross, ESPN reported.
2014: The Year in Music [PHOTOS]