Rep. Adam Schiff (D-CA) subpoenaed U.S. President Donald Trump’s former top aide on Russia and Europe, Fiona Hill, to give a behind closed doors deposition in the impeachment probe despite her agreeing to do so voluntarily.

Schiff is the chairman of the House Intelligence Committee. The Democrat-led House Committees on Oversight and Reform, Intelligence, and Foreign Affairs are leading the impeachment inquiry.

Hill, who served in Trump’s National Security Council (NSC) for over two years, had already agreed to testify Monday. Her deposition is currently underway.

Before Hill’s testimony began, Rep. Jim Jordan (R-OH), the top Republican on the House Committee on Oversight and Reform, told reporters:

We found out just about an hour ago that Chairman Schiff subpoenaed Dr. Hill. She was going to come; she’d agreed to come. She was going to come voluntarily, but he’s going to subpoena her I believe so he can ask certain questions and again keep those secret except for certain things that he wants to leak, the cherry-picked information he wants to leak to the American people.

On Monday, CBS News revealed that Hill was not planning to provide congressional investigators with documents or texts, possibly prompting Schiff to subpoena her.

The news outlet pointed out:

CBS News’ Margaret Brennan reports that Hill is expected to tell lawmakers that President Trump’s personal attorney, Rudy Giuliani, and Ambassador to the European Union Gordon Sondland actively avoided her and the NSC process and ran their own Ukraine policy, according to a source familiar with Hill. Hill, who is testifying voluntarily, does not intend to hand over documents or texts. She officially left the White House in July, but before the July 25 call between Mr. Trump and [Ukrainian President Volodymyr] Zelensky took place.

The former NSC official is testifying despite not knowing much about the July 25 conversation at the center of the impeachment probe.

Trump’s call with Zelensky has embroiled the U.S. president in the unfolding impeachment probe.

An intelligence community “whistleblower” accused Trump of leveraging U.S. aid to Ukraine in exchange for it investigating corruption allegations against Joe Biden and his son, Hunter. The “whistleblower’s” accusations triggered the impeachment inquiry. Trump and Zelensky have denied the claims.

Jordan and other Republican congressmen who have witnessed the deposition provided by the impeachment inquiry witnesses interviewed so far have lambasted Schiff for keeping the testimonies private. The GOP lawmakers argue that at least one of the statements obliterates the Democrats’ claim that Trump made a quid pro quo offer to his Ukrainian counterpart.

On Sunday’s broadcast of CBS’s Face the Nation, Schiff defended carrying out the impeachment inquiry behind closed doors.