UA student Ian Upton, who passed away March 12, died from exposure to the cold, said Dr. Bruce Parks chief medical examiner with the Pima County Medical Examiner’s Office.

Upton, an urban planning senior, had alcohol in his system, which probably contributed to the death, Parks said.

Upton, 21, was found dead in the Rillito riverbed just east of 3750 N. Country Club Road at 8:34 a.m. during spring break.

The cold can kill if internal body temperature drops below 70 degrees, which causes arrhythmia in the heart, Parks said. It is not frequent to see deaths due to cold in Pima County, but cases do occur, Parks said.

Friends of Upton have been coping with his death “”day by day,”” said Stephan Hudnall, a friend of Upton’s who attends Mesa Community College.

“”Losing your best friend is never the easiest thing in the world,”” Hudnall said.

Hudnall and Andrew Busch, a friend of Upton’s at Arizona State University, said Upton was out with friends the night of his death, but they did not know the circumstances that led to his death.

Both had known Upton since middle school.

Hudnall described Upton as “”probably the funniest kid in the whole world.””

UA students might remember Upton as the student who went streaking across the football field three years ago.

“”He was one of those people who … just wanted everyone happy,”” Hudnall said.