Ilya Sutskever, a computer scientist who was born in Russia, grew up in Israel, immigrated to Canada as a teen and contributed to an important AI breakthrough while studying under Geoffrey Hinton at the University of Toronto, is at the centre of tech’s biggest story: the firing of former OpenAI CEO Sam Altman. Here’s what you need to know:

The flip-flop: Sutskever—OpenAI’s chief scientist, co-founder and board member—reportedly led the push to oust Altman on Friday, informing the former CEO of his termination via video chat by reading from a script. He appears to have had a change of heart, however. On Monday morning, Sutskever posted on X that he “deeply regret[s]” his actions and will attempt to “reunite the company.” He also joined over 700 of OpenAI’s employees in signing an open letter calling on the board to resign.

Microsoft, OpenAI’s major investor, has already hired Altman and former president Greg Brockman to lead a new artificial intelligence research unit. OpenAI has named Twitch co-founder and CEO Emmett Shear its new interim CEO.

The background: In 2012, in collaboration with Hinton and other graduate students, Sutskever helped develop groundbreaking software that could identify the content of images by mimicking neural networks in the human brain. Sutskever joined Google along with Hinton, then left to co-found OpenAI in 2016. Tesla CEO Elon Musk, another OpenAI co-founder, has publicly taken credit for recruiting Sutskever to the firm.

Altman reduced Sutskever’s role at the company in October, Bloomberg reported. According to the same report, Sutskever had concerns about Altman’s other ventures, including the crypto company Worldcoin and a proposed chipmaker startup, which were beyond the oversight of OpenAI’s board.

Meanwhile, tensions between the two co-founders reportedly moved to OpenAI’s board. The company’s unusual structure, in which a non-profit wholly owns and controls OpenAI’s for-profit arm, along with some board departures in 2023 left Sutskever and the three independent directors with the majority needed to make changes without notice.

The fear: In a mini documentary by The Guardian, Sutskever expresses simultaneous yearning for and fear of artificial general intelligence, the hypothetical level of AI development at which its capabilities will match and surpass those of humans. He expresses a belief that AI will one day end unemployment, cure disease and eliminate poverty, but may also have goals that are not in alignment with humanity’s. “I think it’s pretty likely the entire surface of the earth will be covered with solar panels and data centres,” he said. “The future is going to be good for the AIs regardless. It’d be nice if it were good for humans as well.”

The division: Other OpenAI staff share Sutskever’s views about the transformative power of AI, but disagree about whether to be optimistic or fearful. Altman reportedly referred to divisions in the company on this issue as “tribes,” according to a 2019 email obtained by The Atlantic. Sutskever was a member of the tribe concerned about AI risk, co-leading a “superalignment” team to ensure the artificial intelligence they were creating would share human values—and, according to The Atlantic, leading employees in a “Feel the AGI!” chant at a holiday party.