Google has concluded its investigation into the firing of prominent AI ethics researcher Timnit Gebru, and it announced some changes to its hiring, firing and research policies in an email from AI leader Jeff Dean to employees Friday.

While Dean did not share the results of the investigation into the circumstances surrounding Gebru's dismissal, he said that the company would enact new policies to "review employee exits that are sensitive in nature." His email, which was obtained by Protocol, said the company will also begin linking performance reviews for vice presidents and above, in part regarding diversity and inclusion goals, and it will report DEI goals and progress to the Alphabet board of directors in quarterly reviews.

The review process for publishing research papers will also change, especially for research that addresses "sensitive issues," according to the email. The process will become more streamlined because "what might be considered sensitive isn't always clear," Dean wrote. Part of the new process will include a review and outline of the kinds of research the company believes it should be conducting. Gebru's departure was mired in internal controversy over a research paper that discussed some of the ethical risks of large-language AI models; Gebru refused to take her name off the paper at Google's demand and then was dismissed shortly afterward.

"I expected nothing more obviously. I write an email asking for things, I get fired, and then after a 3 month investigation, they say they should probably do some of the things I presumably got fired asking for, without holding anyone accountable for their actions," Gebru wrote on Twitter.

Google also announced yesterday that the company's research on responsible AI will be restructured under a new team led by Marian Croak, a long-time Google engineering director. Margaret Mitchell, Gebru's former ethical AI co-lead at Google and founder of the ethical AI team, has been under investigation by Google and without access to her accounts for several weeks, and said she was not informed about the restructuring plans. "And this is how I find out. I'm so glad for all the trust they've rebuilt. It seems I've been completely erased and my team taken," she wrote on Twitter about the news.

"I understand we could have and should have handled this situation with more sensitivity. And for that, I am sorry," Dean wrote in the email.

On Friday afternoon, Mitchell wrote on Twitter: "I'm fired."

This story was updated at 5:31 pm ET to include news of Mitchell's firing.