Google, a subsidiary of Alphabet, expelled scientist Margaret Mitchell on Friday, in a new move that has sparked divisions within the company over academic freedom and diversity, which began since the sacking of AI ethics researcher Tymnet Gibro last December.
Google said in a statement that Mitchell violated the company's code of conduct and security policies by moving electronic files outside the company.
Mitchell - who announced her dismissal on Twitter - did not respond to this statement.
Google's practices in AI ethics have come under scrutiny since the dismissal of Gibro, the scientist who gained fame for exposing bias in facial analysis systems.
Google's dismissal of Gibro prompted thousands of company employees to protest.
She and Mitchell called for more diversity and inclusion among the Google search staff, and expressed concern that the company had begun to censor paper critical of its products.
Gibro said that Google fired her after questioning the order issued by the company's management not to publish a study saying that imitating the language could harm marginalized groups.
Mitchell, a co-author of the study, has publicly criticized the company for firing Gibro and undermining the credibility of its work.
For nearly two years, the two scientists co-led the ethical AI team started by Mitchell.
Zubin Kahramani, director of AI research at Google, and a lawyer for the company informed Mitchell's team of the dismissal order on Friday in a hastily arranged meeting, according to a source familiar with the matter.
The source said a simple explanation was provided for the separation.
The company said that Mitchell's dismissal followed disciplinary recommendations by investigators and the audit committee.
It explained that its violations "included the theft of confidential business-sensitive documents and private data of other employees."
The investigation began on January 19.
Alex Hanna, a Google employee, said on Twitter that the company was waging a "smear campaign" against Mitchell and Gibro, with whom it worked closely.
Google declined to comment on Hanna's comments.
Reuters reported in December that Google provided a new review of "sensitive topics" last year to ensure that research papers on topics such as the oil industry and content recommendation systems would not put the company in legal or regulatory trouble.
Mitchell publicly expressed concern that the policy could lead to censorship of research papers.
Google reiterated to researchers in a note during the meeting on Friday that it is working to improve the previous review of the publication of the papers, and also announced new policies to deal with departing employees of sensitive status in the company and the evaluation of executives.