Two days on the Hill: Facebook's Zuckerberg in the spotlight

News photographers prepare remote cameras hours before Zuckerberg's appearance at a Senate hearing on Tuesday. 

Senators grilled Zuckerberg about election meddling and how Facebook handles user privacy.

Members of the public wait in line before Zuckerberg's appearance before the senators.

Photographers capture the moment Zuckerberg takes his seat.

Senator Deb Fischer, R-Neb., questions Zuckerberg.

Zuckerberg spent five hours in the hot seat on Tuesday, where he took questions from the Senate Judiciary and Commerce Committees. 

Sen. Cory Gardner, R-Colo., listens as Zuckerberg responds.

The hearings were a major test for Zuckerberg. Facebook is confronting its biggest privacy scandal ever  after it was revealed that the data firm Cambridge Analytica misused data from up to 87 million users.

Sen. Kamala Harris, D-Calif., speaks with a colleague.

Zuckerberg said he and other senior executives weren't proactive enough with Cambridge Analytica, but would now use artificial intelligence during elections to stop fake accounts.

Senate staffers remove material from the dais after the hearing.

Zuckerberg appears before a House committee on Wednesday.

Rep. Markwayne Mullin, R-Okla., greets Zuckerberg.

Lawmakers came armed with questions about the nuances of Facebook’s privacy settings and whether the company is properly supplying its users with the knowledge and tools they need to protect themselves.

Zuckerberg leaves the hearing room after two days of testifying on Capitol Hill.

Related: Zuckerberg says his data was part of Facebook's Cambridge Analytica scandal