ChatGPT-maker OpenAI’s co-founder and Chief Scientist Ilya Sutskever recently announced his intention to depart from the artificial intelligence startup.

“After almost a decade, I have made the decision to leave OpenAI,” Sutskever wrote in a post on X/Twitter.

He continued, “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 has contributed immensely in the development of OpenAI. Previously, he worked as a researcher at Google Brain.

The co-founder also played an important role in ousting and rehiring of OpenAI’s CEO, Sam Altman.

Reportedly, Sutskever helped to orchestrate Altman’s exit from the company and later supported an employee letter demanding Altman’s return.

“I deeply regret my participation in the board’s actions,” Sutskever wrote at that time. “I never intended to harm OpenAI. I love everything we’ve built together and I will do everything I can to reunite the company.”

After Altman’s return, Sutskever was immediately removed from the board. Following this, he stayed away from the company’s day-to-day operations for months.

Reacting to Sutskever’s resignation, Altman said in a blog post, “OpenAI would not be what it is without him.”

“I am forever grateful for what he did here and committed to finishing the mission we started together,” Altman added.

Sutskever will be replaced by Jakub Pachocki, who earlier worked as OpenAI’s director of research and led the development of GPT-4 and OpenAI Five, according to the company’s blog.