Donald Trump Jr. arrived on Capitol Hill Thursday morning for a private meeting with the Senate Judiciary Committee, which is probing Russian interference in the 2016 election.

Trump Jr. is expected to face hours of questioning by the Senate Judiciary Committee staff.

Officials have wanted to hear from the president’s eldest son ever since reports emerged of his June 2016 meeting with Russian attorney Natalia Veselnitskaya at Trump Tower. Emails released in July show that Trump Jr. was told before the meeting that it was part of a Russian government effort to help his father.

Democrats have pointed to that meeting to argue collusion between the Trump campaign and the Russian government during the 2016 presidential election. The Trump campaign has denied the accusation.

In July, the Judiciary Committee called on Trump Jr. to testify about Russia’s attempted meddling in the election, but Trump Jr., along with former Trump campaign chairman Paul Manafort, made a deal with the committee to avoid a public hearing, paving the way for a transcribed interview in private.

“In late July, Donald Trump Jr. agreed to provide the Judiciary Committee with documents and a transcribed interview prior to a public hearing. Shortly thereafter, a date for that interview was set and agreed to by both the committee and Trump Jr. This meeting will be conducted under the same terms as previously announced,” Committee Chairman Chuck Grassley, R-Iowa, and Ranking Member Dianne Feinstein, D-Calif., said.

The committee also sought a private interview with the head of the firm behind the infamous anti-Trump dossier. Co-founder of Fusion GPS Glenn Simpson met with committee staff on Aug. 22.

The Associated Press contributed to this report.