OpenAI's chief scientist, Ilya Sutskever, is leaving the company

Ilya Sutskever, OpenAI's co-founder and chief scientist, who in November joined three other board members to force Sam Altman, the company's prominent CEO, before saying he regretted the move, will leave the San Francisco AI company.

Dr. Sutskever's departure, which the company announced in a blog post on Tuesday, closes another chapter in a story that has stunned Silicon Valley and raised questions about whether Mr. Altman and his company are ready to lead the technology industry into the age of artificial intelligence.

Returning to OpenAI just five days after his ouster, Altman reasserted his control and continued his push toward increasingly powerful technologies that had alarmed some of his critics. Dr. Sutskever remained an employee at OpenAI, but never returned to work.

“This is an emotional day for all of us,” Mr. Altman said in an interview. “OpenAI wouldn't exist without him, and he certainly helped shape it.”

“I have made the decision to leave OpenAI,” Dr. Sutskever said in a statement. The company's trajectory has been nothing short of miraculous, and I'm confident that OpenAI will build AGI that is both safe and useful. AGI, or artificial general intelligence, is a technology that hasn't been built yet that can do anything a brain can do.

Dr. Sutskever (38 years old) added that he had started a new project, but did not go into details.

Jacob Paczucki, one of the principal researchers at OpenAI, will replace Dr. Sutskever as chief scientist at the company, which is valued at more than $80 billion, according to a recent fundraising deal.

OpenAI on Monday unveiled a new version of its ChatGPT chatbot that can receive and respond to voice commands, photos and videos, joining tech giants like Google and Apple in the race toward a new kind of talking digital assistant.

Founded in 2015 by Mr. Altman, Elon Musk, and several young researchers, including Dr. Sutskever, OpenAI has long been at the forefront of AI research. Dr. Sutskever's involvement provided the company with immediate credibility. As a graduate student at the University of Toronto, he was part of an artificial intelligence breakthrough involving neural networks, the technology that has driven progress in the field over the past decade.

In late 2022, OpenAI wowed the world with the release of ChatGPT, an online chatbot that can answer questions, write poetry, create computer code, and chat just like people. The technology industry quickly embraced so-called generative AI, technologies that can generate text, images and other media on their own.

The result of more than a decade of research within companies like OpenAI and Google, generative AI is poised to reshape everything from email programs to internet search engines and digital assistants.

Mr. Altman has become a spokesman for the shift toward generative AI, testifying before Congress and meeting with lawmakers, regulators, and investors around the world. In November, OpenAI's board of directors unexpectedly fired him, saying he could no longer be trusted with the company's plan to eventually create artificial general intelligence.

OpenAI's board of directors was composed of six people: three founders and three independent directors. Dr. Sutskever voted with the three outside parties to remove Mr. Altman as CEO and chairman of the board, saying — without providing details — that Mr. Altman had not been “consistently honest in his communications.”

Greg Brockman, OpenAI's chief operating officer and another co-founder, resigned from the company in protest. So did Dr. Pacioki.

Days later, when hundreds of OpenAI employees threatened to quit, Dr. Sutskever said he regretted his decision to fire Mr. Altman and effectively stepped down from the board, leaving three independent members in opposition to Mr. Altman.

Mr. Altman returned to the CEO position after he and the board agreed to replace two members: Brett Taylor, the former CEO of Salesforce, and Lawrence Summers, the former US Treasury Secretary. Mr. Altman regained his seat on the board several months later, as the board expanded to include seven people.

Last year, Dr. Sutskever helped create a Super Alignment team within OpenAI to explore ways to ensure future versions of the technology won't cause harm. Like others in the field, he has become increasingly concerned that artificial intelligence could become dangerous and perhaps even destroy humanity.

Jan Lek, who ran the Super Alignment team alongside Dr. Sutskever, also resigned from OpenAI. His role will be taken over by John Shulman, another co-founder of another company.

In the weeks before Mr. Altman's ouster, Dr. Paciocchi, who helped oversee the creation of GPT-4, the technology at the heart of ChatGPT, was promoted to director of research at the company. After serving below Dr. Sutskever, he was promoted to a position alongside him, two people familiar with the moves said.

After Mr. Altman was reinstated, Dr. Sutskever did not return to work. Mr. Altman indicated that he had hoped to negotiate his return, but that was ultimately not possible.

Dr. Paczucki has effectively served as Chief Scientist since November. After Dr. Sutskever recruited him and others to join OpenAI, he was among the principal investigators on several of the company's most important projects, including, most notably, GPT-4.

“I am grateful to Elijah,” Dr. Pacioki said in an interview. “We have different leadership styles that are complementary in many ways.”

Mr. Altman said he spoke with Dr. Sutskever on Tuesday. “We have pushed — and will continue to push us — to get a feel for AGI,” Mr. Altman said.