CNN  —  OpenAI’s chief scientist and cofounder, who played an instrumental role in CEO Sam Altman’s short-lived ouster from OpenAI in November, announced that he was leaving company on Tuesday. “After almost a decade, I have made the decision to leave OpenAI,” Ilya Sutskever said in a social media post. “I am excited for what comes next — a project that is very personally meaningful to me about which I will share details in due time.” Sutskever played a central role in the dramatic firing – and return – of OpenAI CEO Sam Altman last year, a management crisis that ultimately appeared to strengthen Altman’s position as a leader in the surging field of artificial intelligence. The announcement of Sutskever’s departure comes one day after OpenAI unveiled its latest artificial intelligence model, GPT-4o, in a presentation that impressed onlookers with its capabilities. From OpenAI Related article OpenAI unveils newest AI model, GPT-4o Sutskever’s role at OpenAI will be filled by Jakub Pachocki, previously the company’s director of research, according to the company. Sutskever made headlines nearly six months ago when he voted to remove Altman as chief executive and chairman of the board. CNN contributor Kara Swisher previously reported that the decision to fire Altman was driven by Sutskever’s concerns that Altman had pushed AI technology “too far, too fast.” Days after Altman’s ouster, Sutskever had a change of heart: He signed an employee letter calling for the entire board to resign and for Altman to return. Altman did not stay on the outs for too long. Five days after his firing, Altman returned to the company as CEO, and Sutskever issued a public apology for his role in the corporate drama. “I deeply regret my participation in the board’s actions,” Sutskever wrote on X in November. “I never intended to harm OpenAI. I love everything we’ve built together and I will do everything I can to reunite the company.” In the months since, OpenAI has continued to push advancements of its flagship product, ChatGPT. Its latest model, announced Monday, will be available to unpaid customers and can effectively turn ChatGPT into a digital personal assistant that can engage in real-time spoken conversations. Sutskever played a defining role in OpenAI’s rise to power in the AI scene. In 2019, Altman, Sutskever and Greg Brockman jointly formed OpenAI LP, a for-profit entity within the larger nonprofit company’s structure. A few years later, the company earned a valuation of $90 billion. In a statement, Altman said the news of Sutskever’s departure was “very sad.” “I am forever grateful for what he did here and committed to finishing the mission we started together,” Altman said.