CNN  — 

Facebook (FB) CEO Mark Zuckerberg testified over the course of two days this week before the Federal Trade Commission as part of its antitrust investigation into the company’s business practices, according to a person familiar with the matter.

The testimony, which occurred remotely, comes as the FTC has also sought to review past acquisitions by Facebook and other tech companies to determine whether those deals chilled competition.

And it follows a high-profile congressional hearing in which Zuckerberg and the CEOs of Amazon (AMZN), Apple (AAPL) and Google (GOOGL) defended their companies from antitrust claims.

The FTC declined to comment. Zuckerberg’s testimony was first reported by Politico.

“We are committed to cooperating with the US Federal Trade Commission’s inquiry and answering the questions the Agency may have,” a Facebook spokesperson said in a statement provided to CNN Business.

The FTC routinely conducts interviews as part of its investigations. It is not necessarily a sign that the agency will bring a case. But this week’s interview marks a departure from an earlier FTC investigation into Facebook that resulted in a $5 billion penalty.

In that case, which dealt with Facebook’s handling of the Cambridge Analytica scandal, the commission opted not to interview Zuckerberg or his top lieutenants as they tried to determine whether the company had violated the terms of a 2012 settlement agreement.