The national security aide to Vice President Mike Pence who testified publicly before the House Intelligence Committee gave congressional investigators information about a phone call between Pence and Ukrainian President Volodymyr Zelensky in September, according to a new letter from House Intelligence Committee Chair Adam Schiff (D-CA).

Schiff revealed the existence of the new impeachment evidence in a letter to Pence on Friday. According to the letter, the vice president’s office has classified the information that aide Jennifer Williams provided to investigators about the September 18 Pence-Zelensky phone call. Schiff asked Pence to declassify the supplemental testimony, saying there was no “legitimate” reason to keep the information secret.

Williams provided the House Intelligence Committee with the additional information on November 26, a week after she testified publicly. Schiff asked Pence for a response by December 11.

“The Office of the Vice President’s decision to classify ‘certain portions’ of the Sept. 18 call … cannot be justified on national security or any other legitimate grounds we can discern,” he wrote. “Having reviewed the supplemental submission, the committee strongly believes that there is no legitimate basis for the Office of the Vice President to assert that the information … is classified.”

During her initial deposition before the House Intelligence Committee, Williams told investigators the September 18 call was just a follow-up to a meeting with Zelensky earlier in September. Williams described the call as “very positive” and said there was no mention of investigations, which have formed the basis of the House impeachment inquiry.

Williams made waves when she described the infamous July 25 call between President Trump and Zelensky as “unusual and inappropriate.” That call, in which Trump attempts to pressure Zelensky into opening investigations into his political rivals, is at the center of a whistleblower complaint that launched the impeachment probe.

Read the letter below: