Google is investigating artificial intelligence researcher Margaret Mitchell, who co-leads the company’s Ethical AI team, and has locked her corporate account, Axios reports. The news comes a little over a month after another prominent AI ethicist, Timnit Gebru, said she was fired by the company. Mitchell’s account has now reportedly been locked for “at least a few days” but she hasn’t been fired, according to a tweet from Gebru. Mitchell did not immediately respond to a request for comment.

In a statement given to Axios, Google said it was investigating Mitchell after its systems detected an account had “exfiltrated thousands of files and shared them with multiple external accounts.” According to an Axios source, Mitchell had been using a script to go through her messages, finding examples of discriminatory treatment of Gebru. Last week, Mitchell tweeted to say she was documenting “current critical issues from [Gebru’s] firing, point by point, inside and outside work.”

Google said its security systems automatically lock corporate employee accounts “when they detect that the account is at risk of compromise due to credential problems or when an automated rule involving the handling of sensitive data has been triggered.”

“We explained this to the employee earlier today,” Google said, “We are actively investigating this matter as part of standard procedures to gather additional details.”

Mitchell has previously tweeted in support of Gebru, and has been critical of Google and other big tech companies for their approaches to diversity and systematic bias. Yesterday she tweeted to criticize Google CEO Sundar Pichai’s approach towards workplace diversity.

Google faced widespread criticism after Gebru left the company. Bloomberg reports that thousands of internal employees and external academics and campaigners signing a petition in support of the AI researcher. The company has faced ongoing criticism for its work on Project Maven, an AI project designed to improve military drone strikes. Opposition to the project was named as a key reason when Google employees announced plans to unionize earlier this year.