On Sunday morning’s “Meet the Press,” former Cambridge Analytica staffer Christopher Wylie made a number of stunning revelations about the data mining firm hired by Trump during the 2016 election. Cambridge Analytica has come under intense scrutiny in recent weeks, following media reports that the firm improperly obtained the data of millions of Facebook users in order to use it to sway elections.

Wylie said on Sunday that the number of Facebook users whose data was gathered by the British firm could “absolutely” surpass the social media giant’s own estimate of 87 million. He also said that he is planning to fully cooperate with both congressional and justice department probes into Russian interference in the US election, and that he believes compromised Facebook data could be accessible to many people and stored in different countries, including Russia.

WATCH: Chris Wylie, former Research Director at Cambridge Analytica, tells Chuck that he has been contacted by American authorities about the release of 87 million Facebook users' data. #MTP pic.twitter.com/MTpbG5q6PQ — Meet the Press (@MeetThePress) April 8, 2018

Wylie has previously suggested in interviews with a number of media outlets that the Facebook data harvested by Cambridge Analytica was used by the company to sway the 2016 election. “We exploited Facebook to harvest millions of people’s profiles. And built models to exploit what we knew about them and target their inner demons,” Wylie told the British Observer. “That was the basis the entire company was built on.”

Wylie’s statements come just days before Facebook founder Mark Zuckerberg is scheduled to testify in Washington before three different congressional committees—first before a joint hearing of the Senate judiciary and commerce committees on Tuesday, and then again on Wednesday before the House Energy and Commerce Committee. It’s expected that he’ll be grilled about steps Facebook is taking to protect user data, and to prevent foreign powers from exploiting the platform to influence elections.

In recent weeks, Facebook has admitted that it learned that Cambridge Analytica was harvesting its users data more than two years ago. The company contacted the political research firm and Cambridge Analytica promised to delete the data. Facebook never followed up. In an NBC interview last week, Facebook’s chief operating officer Sheryl Sandberg acknowledged that the company should have gone public with the data breach earlier.