Former OpenAI chief scientist Ilya Sutskever testified on Monday that he spent about a ​year gathering evidence for the ChatGPT maker’s board that CEO Sam Altman had displayed a “consistent pattern of lying.”

During his ‌testimony in a legal fight between OpenAI and Elon Musk, the top AI researcher ​confirmed he had been thinking about taking action to remove Altman as CEO for ⁠at least one year prior to his November 2023 board vote to oust Altman.

Sutskever said he had prepared a document gathering evidence of Altman’s dishonesty at the request of OpenAI’s board, and confirmed Altman’s conduct included “undermining and pitting executives ‌against one another.” He said he had discussed removing Altman with then chief technology officer Mira Murati after the two discussed Altman’s behaviour “for a long time.”

Altman is expected to ‌testify as soon as Tuesday.

Sutskever had mentioned in a prior deposition that his document ran ‌for ⁠52 pages.

Altman’s conduct was “not conducive to any grand goal”, including the creation of safe ⁠AGI, Sutskever said as he testified in a California courtroom.

Sutskever had played a key role in Altman’s dramatic firing and rehiring in November 2023 — at the time, Sutskever was on OpenAI’s board and helped orchestrate Altman’s firing.

But worried that the company could ​collapse, he later expressed regret over his “participation ‌in the board’s actions” and voted to reinstate Altman, who has since led the company and is now the central figure in OpenAI’s fight against Musk.

His testimony comes in the third week of a trial that could determine the future of OpenAI, which has been raising billions of dollars ‌from investors to build out its computing power ahead of a potential trillion-dollar IPO.

Musk, a ​co-founder of OpenAI who left the board in 2018, has accused the company and Altman of abandoning its nonprofit roots and becoming a for-profit company to enrich ⁠themselves. Musk is seeking $150 billion in damages from OpenAI and its backer Microsoft to be paid to the nonprofit, and for Altman and President Greg Brockman to be removed from their roles.

Musk had testified in the ‌first week of the trial that he knew about early discussions around turning OpenAI into a for-profit but was reassured by Altman it would remain a nonprofit.

Closing arguments for the trial will happen on Thursday, U.S. District Judge Yvonne Gonzalez Rogers said.

Sutskever disclosed on Monday that his ownership stake in OpenAI was worth about $5 billion as of November 2025, and about $7 billion currently.

He also confirmed that after Altman’s brief ouster, the remaining OpenAI board members met with rival Anthropic about ‌a proposal for the Claude chatbot creator to merge with OpenAI and take over its leadership. He said he was “not ​excited” about merging OpenAI with another company.

Sutskever said he avoided the internet for most of the weekend after the board vote to fire Altman, and that he was ⁠not initially aware of contingency plans like Microsoft’s proposal to absorb Altman, Brockman, and other OpenAI employees into a new ⁠subsidiary.

He left OpenAI in 2024 and has since launched an AI startup called Safe Superintelligence.

Earlier on Monday, Microsoft CEO Satya Nadella took the stand, characterising the tech giant’s investment in ‌OpenAI as a “calculated risk,” emphasising that Microsoft considered its early investments to be worthwhile for marketing benefits. Former and current OpenAI executives, including Brockman, Murati and Shivon Zilis, have already testified in the trial.