Alyssa Byrne, the 19-year-old from Petaluma found dead last week in South Lake Tahoe, apparently took a wrong turn New Year's Eve and wandered a short distance through snow before shedding her ski jacket and dying in the bitter cold on a snowbank, authorities said Monday.
Byrne was found dead three days later. Her boot prints -- the only ones in the vicinity -- suggested disorientation that may have been caused by alcohol consumption, hypothermia or both, El Dorado County Sheriff's Lt. Pete Van Arnum said.
"I don't want to speculate," he said, although he confirmed investigators had reports Byrne had been drinking while in town with friends for a music festival.
He noted advanced hypothermia causes confusion and deteriorating cognition. Victims can become disoriented and lose judgment.
"It was subzero that night and, depending on how long she was out in the cold, that could have affected her," Van Arnum said.
Experts say it's common for those with fatal hypothermia to remove clothing shortly before death because of physiological changes that cause a spreading sense of warmth.
The National Weather Service said it was minus 8 degrees overnight New Year's Eve in the area.
It's unclear when Byrne died. The Sacramento County Coroner's Office, which is handling the death investigation, has put the official date at Jan. 4, the day she was found. Authorities have said there were no signs of traumatic injury or foul play.
Douglas County, Nev., investigators, who led the initial search for Byrne, said she last used her cellphone at 11:53 p.m. New Year's Eve and was believed to have collapsed after leaving the final concert of a three-day music festival at Lake Tahoe Community College, a half-mile from where her body was found.
The 2011 Casa Grande High School graduate had driven Dec. 29 to Lake Tahoe with three friends with whom she attended the festival and shared a room at the Horizon Casino Resort in nearby Stateline, Nev.