The nine skiers killed in a horrific avalanche near Lake Tahoe in February all died of asphyxiation — as police  wrapped their investigation into the devastating disaster.

The Nevada County Coroner’s Office announced the findings nearly seven months after the snow slide on Castle Peak left six backcountry skiers and three guides dead.

The Nevada County Sheriff’s Office also said it had finished its investigation into potential criminal negligence on the part of the guiding group and sent its findings to prosecutors for review.