Google has fired another researcher who specialized in the ethics of artificial intelligence, just three months after the company’s treatment of one of the researcher’s colleagues caused an uproar over Google’s record on diversity and inclusion.

The move is likely to raise further questions about how the giant technology company is handling a growing wave of employee activism over everything from the company’s work with the U.S. military to its handling of sexual harassment cases and its treatment of contract workers.

Margaret Mitchell, who led Google’s team of A.I. ethics researchers within its Google Brain artificial intelligence division, said on Twitter Friday that she was fired by the company. Until November, Mitchell’s co-lead on the A.I. ethics team had been Timnit Gebru, a prominent Black computer scientist who said Google fired her after she raised questions about the company’s treatment of Black employees amid a dispute with company manager’s over the publication of a research paper in which she and members of her team also raised ethical concerns about some of the A.I. systems Google has helped develop. Google has insisted that Gebru resigned.

Google confirmed that Mitchell’s employment had been terminated and said in a statement that an investigation had found Mitchell had violated the company’s code of conduct and security policies. It said she had removed “confidential business-sensitive documents and private data of other employees” from the company’s internal computer networks.

Mitchell’s firing comes on the same day that Google chief executive Sundar Pichai sent an email to employees that included an acknowledgement from the top executive of its research division that the situation involving Gebru “should have been handled with more sensitivity,” according to a report in Bloomberg News. It also came just days after Google announced a reorganization of its A.I. ethics efforts across the company, consolidating several different teams that touched on A.I. ethics under the supervision of Marian Croak, one of the company’s most senior Black executives and scientists.

In Pichai’s e-mail, the CEO said that Google will begin grading executives on whether they meet workforce diversity goals and hire more human resources executives, according to Bloomberg.

Mitchell had been publicly critical of Google’s treatment of Gebru. On her Twitter account she pinned a post linking to a document she wrote saying that racism and sexism at Google had been at the root of Gebru’s firing. Mitchell said she was locked out of the company’s computer networks five weeks ago after she had used automated software to scan through emails for examples of Google discriminating against Gebru.

The company said at the time its cybersecurity software had detected Mitchell removing large amounts of data from the company’s networks and had automatically suspended her access pending further investigation. Mitchell was a member of Google’s newly-formed Alphabet Workers Union, the company’s first officially-recognized organized labor group, and at the time the company first suspended her network access the union issued a statement saying it was “concerned” that Google was retaliating against Mitchell for her activism and her support of Gebru.

What is clear is that firing Mitchell, along with the reorganization of the A.I. ethics research group, is only likely to heighten concerns both inside and outside Google about the company’s commitment to the ethical development of artificial intelligence as well as its record on diversity and inclusion.