In a surprise move, OpenAI’s chief technology officer announced on Wednesday that she will soon be leaving the company after six and a half years.

In a note shared with the company and then posted to Twitter/X, Mira Murati wrote that she was leaving technology company ChatGPT. “After much consideration, I have made the difficult decision to leave OpenAI… I am stepping down because I want to create the time and space for myself to conduct my own explorations,” she said.

CEO Sam Altman responded kindly to Murati’s departure, writing on X: “I have tremendous gratitude to her for what she helped us build and achieve, but most of all I feel personal gratitude to her for the support and love during all the difficult times. I am excited to see what she does next.”

Before her announcement, Murati’s departure did not seem imminent. She was one of the public faces of OpenAI and continued to promote the company’s work in her final weeks, particularly in explaining technical capabilities. She led demonstrations of the new products at events for software developers and was available for interviews about the company’s work.

In June, she made what appeared to be a veiled threat against artists and writers during a talk at Dartmouth. OpenAI was sued for allegedly violating the copyright of writers and newspapers.

“Some creative jobs may disappear, but maybe they shouldn’t have existed in the first place,” Murati said.

Murati was one of the highest-ranking executives at OpenAI, and her departure further thins the ranks of the leadership team. In November, she took over as head of the well-known startup after its board ousted Altman. In May, OpenAI’s chief scientist Ilya Sutskever resigned, raising concerns about the company’s safeguards against misuse of its AI. Former head of security Jan Leike left the company the same month. Co-founder John Schulman left the company in August for Anthropic, a rival AI startup backed by Amazon. Last week, Sutskever announced the formation of his own startup with $1 billion in new investment.

OpenAI is currently seeking new investments that would value the company at over $100 billion. Microsoft has already spent $10 billion on OpenAI, taking a 49 percent stake, and is likely to fund the company even more. Thrive Capital has announced it will invest $1 billion in OpenAI; Nvidia and Apple are also reportedly participating in the funding round. OpenAI launched ChatGPT in 2022.