OpenAI co-founder Ilya Sutskever said Tuesday that he’s leaving the Microsoft-backed startup. “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 wrote in an X post on Tuesday.

The departure comes months after OpenAI went through a leadership crisis in November involving co-founder and CEO Sam Altman. Almost all of OpenAI’s employees signed an open letter saying they would leave in response to the board’s action.

In March, OpenAI announced its new board and the wrap-up of an internal investigation by U.S. law firm WilmerHale into the events leading up to Altman’s ouster. Altman rejoined OpenAI’s board, and three new board members were announced.

Altman shared his thoughts as Sutskever leaves, expressing sadness at the departure of someone he considers “one of the greatest minds of our generation.” Research director Jakub Pachocki will replace Sutskever as chief scientist.

OpenAI has announced new board members, including former Salesforce co-CEO Bret Taylor and former Treasury Secretary Larry Summers. Microsoft obtained a nonvoting board observer position.

News of Sutskever’s departure comes a day after OpenAI launched a new AI model and desktop version of ChatGPT, along with an updated user interface, the company’s latest effort to expand use of its popular chatbot.