SOUTH LAKE TAHOE  (AP) — A California teen who went missing in South Lake Tahoe on New Year's Eve and was found a few days later near a snow bank likely died of hypothermia and had drugs in her system, according to autopsy results released Monday.

Petaluma resident Alyssa Byrne, 19, had attended the outdoor SnowGlobe Music Festival with friends, but deputies said she never made it back to her hotel about three miles away in Stateline, Nev.

El Dorado County sheriff's Lt. Pete Van Arnum cited hypothermia as the probable cause of death. In a statement, authorities listed methamphetamine toxicity as another significant factor and said Byrne had low levels of other psychoactive drugs in her blood.

Van Arnum declined to specify the other drugs that were found, citing the family's request.

Officials speculated that Byrne may have tried to walk to the hotel to avoid long shuttle bus lines and became disoriented.

Her disappearance in the freezing weather touched off a multi-day search, with friends and family members posting fliers and pleading for information on the case.

A utility worker found Byrne's body on Jan. 4 along Pioneer Trail, about a mile from the festival site at Lake Tahoe Community College. Her body was near the roadway and obstructed from view by a snow bank.

Byrne worked as a restaurant hostess in Petaluma, about 40 miles north of San Francisco, and was taking classes at the Santa Rosa Junior College campus there to become a firefighter-paramedic.

The SnowGlobe Music Festival tilts toward electronic dance music but also features rap, hip-hop and electro-funk. It drew about 40,000 people over its three-day run.