The row within Google's Ethical AI team is set to escalate after a second researcher was fired in the space of three months. Lead artificial intelligence ethics researcher Margaret Mitchell was fired on Friday following the tech giant's controversial dismissal in December of her black colleague Dr. Timnit Gebru. Gebru, an outspoken diversity advocate and well-respected researcher in the field of ethics and the use of artificial intelligence, said she was fired from Google for sending an internal email accusing the company of "silencing marginalized voices." In a statement about Mitchell's dismissal, Google said it had "confirmed that there were multiple violations of our code of conduct, as well as of our security policies, which included the exfiltration of confidential business-sensitive documents and private data of other employees." Sources suggest that Mitchell may have been looking for corporate correspondence that could have supported Gebru's claim of harassment and discrimination.