New case alleging chatbot involvement in mass murder: Bigger disaster, smaller AI involvement

Today, April 29, 2026, a new case, Stacey,. Altman, was filed in a California federal court against OpenAI, alleging the chatbot ChatGPT-4o “played a role” in the Tumbler Ridge Mass Shooting in British Columbia in February 2026, in which eight people including six children were killed, twenty-seven people were wounded, and the shooter committed suicide. This is by far the largest disaster involving a chatbot to be alleged in court, the largest cases previously alleged having been one murder plus one suicide in one case, and an unexecuted plan for a mass murder in another case.