Ilya Sutskever has announced on X, formerly known as Twitter, that he’s leaving OpenAI almost a decade after he co-founded the company. He’s confident that OpenAI “will build [artificial general intelligence] that is both safe and beneficial” under the leadership of CEO Sam Altman, President Greg Brockman and CTO Mira Murati, he continued. In his own post about Sutskever’s departure, Altman called him “one of the greatest minds of our generation” and credited him for his work with the company. Jakub Pachocki, OpenAI’s previous Director of Research who headed the development of GPT-4 and OpenAI Five, has taken Sutskever’s role as Chief Scientist.

While Sutskever and Altman praised each other in their farewell messages, the two were embroiled in the company’s biggest scandal last year. In November, OpenAI’s board of directors suddenly fired Altman and company President Greg Brockman. “[T]he board no longer has confidence in [Altman’s] ability to continue leading OpenAI,” the ChatGPT-maker announced back then. Sutskever, who was a board member, was involved in their dismissal and was the one who asked both Altman and Brockman to separate meetings where they were informed that they were being fired. According to reports that came out at the time, Altman and Sutskever had been butting heads when it came to how quickly OpenAI was developing and commercializing its generative AI technology.

Both Altman and Brockman were reinstated just five days after they were fired, and the original board was disbanded and replaced with a new one. Shortly before that happened, Sutskever posted on X that he “deeply regre[tted his] participation in the board’s actions” and that he will do everything he can “to reunite the company.” He then stepped down from his role as a board member, and while he remained Chief Scientist, The New York Times says he never really returned to work.

Sutskever shared that he’s moving on to a new project that’s “very personally meaningful” to him, though he has yet to share details about it. As for OpenAI, it recently unveiled GPT-4o, which it claims can recognize emotion and can process and generate output in text, audio and images.