The nine individuals who died in a devastating avalanche near Lake Tahoe in February all succumbed to asphyxiation, according to findings released by the Nevada County Coroner’s Office. The announcement comes nearly seven months after the snow slide on Castle Peak claimed the lives of six backcountry skiers and three guides.

The Nevada County Sheriff’s Office has also completed its investigation into potential criminal negligence by the guiding group. The findings have been forwarded to prosecutors for review.

The avalanche occurred on Castle Peak, a popular backcountry skiing destination, in February. The victims were buried under up to 8 feet of snow.