The identical twin brother of Lt. Col. Alexander Vindman, the top Ukraine expert on the National Security Council who testified this week before House lawmakers in the Trump impeachment probe, may also be called to testify, according to a report.

Yevgeny Vindman, also an Army lieutenant colonel, works in the White House in an office next to his brother as an NSC lawyer handling ethics issues.

Alexander Vindman allegedly told investigators that his sibling had witnessed the decision to move the transcript of President Trump’s July 25 phone call with his Ukrainian counterpart, Volodymyr Zelensky, to a top secret server, according to the Wall Street Journal.

House committees have contacted Yevgeny’s lawyer, although no decision has been made, a person briefed on the outreach told the news outlet.

Unlike Alexander, Yevgeny didn’t listen in on the conversation between the two leaders, during which Trump asked Zelensky to investigate former Vice President Joe Biden and his son Hunter while almost $400 million in aid was being withheld from Ukraine, a source told the Journal.

But Yevgeny was allegedly present when Alexander, at the direction of his superiors, reported the phone call to the NSC’s general counsel, John Eisenberg, a person familiar with the colonel’s testimony told the paper.

Gordon Lang, Yevgeny’s attorney, declined to comment to the Journal.

White House deputy press secretary Hogan Gidley told the outlet that the White House “will not discuss the internal deliberations of the White House Counsel’s Office.”