Army Lt. Col. Yevgeny Vindman, an NSC lawyer specializing in ethics, may be asked to testify in the wake of his twin brother’s, Lt. Col. Alexander Vindman’s, bombshell hearing this week.

According to the Wall Street Journal, Yevgeny Vindman witnessed the decision to move the call memo of President Donald Trump’s conversation with Ukraine President Volodymyr Zelensky to the secure server. During that conversation, Alexander Vindman also voiced his concerns to NSC lawyer John Eisenberg about the content of the call.

Eisenberg is slated to testify before the House committees on November 4.

House committees have contacted Yevgeny Vindman’s lawyer, but no decision has yet been made.