Former Olympic gold medalist Bode Miller's brother, Chelone, was found dead in his van around Mammoth Lakes, Calif. Sunday.

The 29-year-old snowboarder was unresponsive inside his van when somebody called 911.

The Mono County Sheriff's Office confirmed his death Monday in a statement. The cause of death is being investigated, but authorities said in that statement that foul play is not suspected. A call to the sheriff's office dispatch was made around 12:45 p.m. Sunday. When paramedics, fire department and deputies arrived on the scene, "it was determined that Mr. Miller was deceased," according to the statement.

"Chelone Miller was an aspiring elite athlete who had made great progress as a snowboardcross rider this past season. We are all deeply saddened at the news of his death and extend our condolences to the entire Miller family," U.S. Ski and Snowboard Association President Bill Marolt said in a statement on the team's website.

Miller was attempting to become a member of the U.S. team for snowboardercross at the 2014 Winter Olympics in Sochi. Nicknamed Chilly, Miller was living in Easton, N.H. as he was attempting to follow in the footsteps of his brother Bode. Bode Miller won an Olympic gold medal in 2010.

In March, Chelone Miller won the Rahlves Banzai Tour overall title courtesy of a victory at Sugar Bowl in California. He also finished Miller finished fourth at the 2013 U.S. Snowboarding Grand Prix in Canyons, Utah.

Several Olympic athletes took to Twitter to express their condolences:

-Freestyle skier and two-time Olympian Emily Cook: "Broken-hearted to hear of the passing of Chelone Miller. Sending love and prayers to Bode, friends and family."

-Snowboarder Elena Hight: "My heart goes out to (at)MillerBode and his family. So sad for the loss of such a great person. (hash)RIPchilly."

Bode Miller is a five-time Olympic medalist in alpine skiing. He sat out the 2012-13 World Cup season while recovering from a knee injury.