NEVADA CITY, California – A report commissioned by the guide company that was leading a backcountry ski party near Lake Tahoe in February when an avalanche killed nine skiers attributed no direct blame to the company.

The report details the movements of the group of backcountry skiers led by Blackbird Mountain Guides after it left the Frog Lake Huts, near Donner Pass in California, during a major snowstorm on Feb 17.

It leans on previously reported news media accounts, the GPS tracks of two party members and avalanche and weather data. It includes accounts of Blackbird guides, including the lone surviving guide as well as the owner, Zeb Blais, who was not on the trip but joined the search-and-rescue effort.

The report draws no conclusions and does not say if mistakes were made. And it does not ask or address a key question: Why did the 15-member group leave the huts in the snowstorm rather than staying sheltered?

The exact cause of the avalanche remains unclear.

“It is not known, nor will ever be known, whether the avalanche was naturally triggered, or triggered by the weight of the group,” the report said.

The aftermath of the avalanche has been clouded by possible legal ramifications for Blackbird and Blais. The sheriff’s department in Nevada County, California, where the avalanche occurred, said on Aug 7 that the case remained open and was under review by the district attorney. Lawsuits from victims or families are possible, too, though none have been filed.

On Aug 6, the sheriff’s department released heavily redacted coroner reports for the nine victims. All died of asphyxia “due to burial in snow during avalanche”, the coroner said.

The report contains two parts. The bulk is an “independent preliminary report” prepared by Don Sharaf, fo...