After initially saying that “yes,” Facebook had been served with subpoenas from Special Counsel Robert Mueller’s office, Facebook founder Mark Zuckerberg said Tuesday that he was “not aware” if the company had been subpoenaed.

Zuckerberg did affirm during a joint hearing of the Senate Judiciary and Commerce Committees, however, that he believed Facebook employees had been interviewed by Mueller’s team, and affirmed that Facebook was working with Mueller’s office.

The Facebook founder said he had not personally been interview by Mueller’s team.

“I want to be careful here, because that — our work with the special counsel is confidential, and I want to make sure that, in an open session, I’m not revealing something that’s confidential,” Zuckerberg told Sen. Patrick Leahy (D-VT), whose questions he was responding to.

“I understand,” Leahy said. “That’s why I made clear that you have been contacted, you have had subpoenas.”

“Actually, let me clarify that, I actually am not aware of a subpoena,” Zuckerberg said. “I believe that there may be, but I know we are working with them.”