Three U.S. House of Representatives committees investigating the President Donald Trump impeachment inquiry denied Colorado’s U.S. Rep. Doug Lamborn the ability to read closed-door testimony of former State Department Official Kurt Volker, according to a Wednesday tweet from the congressman.

“Impeachment is a serious process. It should be open, fair and transparent,” said Lamborn, a Republican from Colorado Springs, as reported by CPR. “And that means members of Congress should be able to see what the evidence is.”

Lamborn is not a member of the Intelligence, Oversight or Foreign Affairs committees, which are overseeing the impeachment inquiry of President Donald Trump.

Today, I was denied access to read the testimony of Kurt Volker in the SCIF. As a member of Congress, I demand access to review documentation that is vital to the process of impeachment. The secret hearings of Adam Schiff are unacceptable and a stain on our democracy.

– Rep. Doug Lamborn (@RepDLamborn) October 16, 2019

Democratic Rep. Adam Schiff, the chairman of the Intelligence Committee, released a statement explaining that members of both parties and their attorneys were able to ask questions of witnesses in hearings.

“The reasons for conducting interviews in private are sound and based on the best interests of a thorough and fair investigation,” Schiff wrote. He cited the lack of an independent prosecutor from the Justice Department as the reason for Congress’s actions. The Constitution grants Congress the ability to set its own rules.

Schiff also referred to precedent in previous presidential impeachments and more recent testimony from Trump associates in defending the need for keeping witness statements private.

“It is of paramount importance to ensure that witnesses cannot coordinate their testimony with one another to match their description of events, or potentially conceal the truth. I am particularly sensitive to that issue given that during the Intelligence Committee’s investigation into Russia’s election interference, one witness, Michael Cohen, lied to the committee about highly relevant issues and ultimately pleaded guilty for those lies,” he said.