President Donald Trump and top House Republicans are ramping up a sweeping investigation into former President Joe Biden’s use of a mechanical signature device known as the autopen, raising questions about the legitimacy of executive actions taken during Biden’s presidency — especially a wave of last-minute pardons signed with the device.

The investigation, led by House Oversight Committee Chairman James Comer (R-KY), gained traction after the Washington Examiner first reported on Friday about Comer’s plans for the committee to investigate whether Biden personally authorized all of his clemency orders and executive actions or whether his aides, acting on his behalf, used the autopen without valid authority.