James Gates’s lawsuit, filed in San Francisco County Superior Court, says Cheryl Gates began using the chatbot in early 2025 to discuss work and marital problems. Her conversations allegedly shifted to poisoning, including questions about oleander and whether it could be concealed in food or drink.

Mr Gates says he became violently ill in July 2025 and later found a note listing oleander and prescription drugs, alongside instructions to clear conversations and log out of ChatGPT.

Cheryl was charged with attempted murder and contaminating food or drink in 2025. Prosecutors dropped the case in April 2026, citing insufficient evidence, according to the lawsuit.

The suit makes nine claims, including negligent design and failure to warn. OpenAI said it had banned the user and provided information to law enforcement.