An expert analysis found that 18-year-old Jesse Van Rootselaar, who carried out a deadly shooting at Tumbler Ridge Secondary School in Canada before killing herself, had a long online history involving firearms, mass violence and graphic “gore” content.

Analysts from the Institute for Strategic Dialogue said she was active on WatchPeopleDie, a website known for hosting violent material and previously linked to other attackers.

Her online activity reportedly escalated over time, shifting from video games to gun posts, drug use, mental health struggles and frequent comments on violent content, as well as a mass shooting simulation created on Roblox.

Police had previously responded to mental health incidents at her home, and she had been apprehended under British Columbia’s Mental Health Act, CBS News has reported.

The attack killed six people — most under 13 — as well as her mother and 11-year-old brother, marking Canada’s deadliest school shooting since the 1989 massacre at École Polytechnique in Montreal.