House Oversight Committee Chairman James Comer (R-KY) issued a subpoena Tuesday to former White House deputy chief of staff Annie Tomasini as part of an escalating investigation into former President Joe Biden’s mental fitness and final clemency decisions while in office.

The Kentucky Republican heading up the investigation into former President Joe Biden's use of the "autopen" to sign documents sent out his own correspondence related to the probe that was "signed" digitally,

House Oversight Committee Chairman James Comer on Tuesday subpoenaed Joe Biden's deputy chief of staff when Biden was president. The committee had requested the former White House official, Annie Tomasini, to appear for a deposition on Friday.

The House Oversight Committee is probing whether former President Biden's top aides covered up signs of mental decline.

Rep. James Comer (R-KY) speaks to reporters after taking the closed-door testimony of Biden-era White House physician Dr. Kevin O'Connor.

The House Oversight Committee is expecting Dr. Kevin O’Connor, former President Joe Biden’s physician, to appear before the House Oversight Committee on Wednesday despite his request to delay his scheduled deposition.

Chairman of the House Oversight Committee Rep. James Comer, R-Ky., discusses the FBI’s Russian collusion investigation and former President Joe Biden’s alleged autopen use on ‘Hannity.’