James Cody Bryant, a 30-year-old resident of Bellingham, Washington, was arrested and charged in connection with the Tumbler Ridge school shooting in British Columbia.
US authorities allege Bryant communicated with shooter Jesse Van Rootselaar for six months, offering advice, financial support, and livestreaming help.
Van Rootselaar killed her mother, stepbrother, and six others at Tumbler Ridge Secondary School before dying by suicide in February.