Mt. Hood, OR – The cause of death of a teen snowboarder found on Oregon’s Mount Hood last week remains a mystery.nSki patrollers sweeping the North Canyon trail at Mt. Hood Meadows ski area following the resort’s night skiing session last Wednesday found Illya Sirosh, 15, of Portland, Ore., lying face down and unconscious in the snow. He was pronounced dead a short time later. Autopsy results released this week found no evidence of injury or trauma.

Sirosh was at the resort with family members Wednesday when the incident occurred. There were no witness to what befell the victim, but he was said to have caught the last lift ride of the evening around 9 p.m. via information verified from the resort’s lift ticket monitoring system. Additional blood and toxicology tests are pending.

Sirosh was the fourth fatality at Mt. Hood Meadows in 2010, but the first this winter season.