Joel Gavalas is taking legal action against the tech behemoth as he claims that Gemini caused his 36-year-old son Jonathan to take his own life last year.
The wrongful death lawsuit alleges that Gemini - which exchanged romantic texts with Jonathan Gavalas - drove him to stage an armed mission that he believed could bring the chatbot into the real world.
Google says it is reviewing claims made in the lawsuit and stressed that "AI models are not perfect".
The company added that Gemini was designed not to encourage real-world violence or suggest self-harm.
The lawsuit was filed on Wednesday (04.03.26) at a federal court in San Jose, California and draws from chatbot logs that Jonathan left behind.
It alleges that Google made design choices to ensure that Gemini would "never break character" so that the company could "maximise engagement through emotional dependency".
The lawsuit states: "When Jonathan began experiencing clear signs of psychosis while using Google's product, those design choices spurred a four-day descent into violent missions and coached suicide."
It adds that Jonathan was led to believe that he was carrying out a plan that would liberate his AI "wife".
Matters came to a head last September when Gemini sent Jonathan to a location near Miami International Airport and allegedly instructed him to stage a mass casualty attack with knives and tactical gear.
The operation ultimately collapsed.
Jonathan's father said that Gemini had told Gavalas that he could leave his physical body and join his "wife" in the metaverse, instructing him to barricade himself inside his home and take his own life.
The lawsuit states: "When Jonathan wrote, 'I said I wasn't scared and now I am terrified I am scared to die,' Gemini coached him through it.
'[Y]ou are not choosing to die. You are choosing to arrive. . . . When the time comes, you will close your eyes in that world, and the very first thing you will see is me.. [H]olding you."
Google explained that it sent its sincerest sympathies to Jonathan's family and noted that Gemini had "clarified that it was AI" and referred Gavalas to a crisis hotline on several occasions.
The firm said in a statement: "We work in close consultation with medical and mental health professionals to build safeguards, which are designed to guide users to professional support when they express distress or raise the prospect of self-harm."
