A former U.S. attorney appointed to investigate the pardons President Biden issued in his final hours in the White House, Ed Martin, has announced that a probe is officially under way. 

“The integrity of the American Pardon system requires that we examine the Biden pardons and who did what. We will get to the bottom of it. Count on us,” Mr. Martin, who serves as U.S. pardon attorney and weaponization tsar in the Department of Justice, wrote Sunday night in a post on X.

Hours before President Trump took the oath of office on January 20, the White House announced pardons for the former director of the National Institute of Allergy and Infectious Diseases, Anthony Fauci, and for a former chairman of the Joint Chiefs of Staff, General Mark Milley. 

With less than 30 minutes left in his term, Mr. Biden pardoned members of his family, including his brother, James B. Biden, wife Sara, sister Valerie Biden Owens, brother-in-law John T. Owens, and brother Francis W. Biden. The former president had pardoned his son, Hunter, for tax and gun crimes a month earlier.

The investigation into the 11th-hour pardons follows an announcement by Representative James Comer, chairman of the House Oversight Committee, that he is opening a House investigation. The Kentucky Republican charged that evidence suggests that not only were pardons allegedly issued with minimal oversight during Mr. Biden’s final days and weeks in office, but several executive orders in his final months may have also been signed using an autopen.

“Joe Biden wasn’t capable of making decisions; he wasn’t coherent,” Mr. Comer said, suggesting White House staffers may have been responsible for key actions under the Biden administration during its concluding months. 

“We think we’ve identified who the staffers are,” he said on Fox News. “We’re going to bring everyone that we believe was involved in any role with the use of the autopen. We’re going to invite them to come in for a transcribed interview; if they won’t, then they will receive a subpoena. They will have a full-blown deposition — but we want to find out who was actually making the decisions in the White House.”

President Trump has called into question the validity of the pardons issued by his predecessor, describing them in an X post as “VOID, VACANT, AND OF NO FURTHER FORCE OR EFFECT.” Mr. Trump suggested that Mr. Biden was unaware of the decisions being made at the time, saying, “He did not know anything about them!” 

The confirmation that an investigation is under way comes after the release of audio recordings of Mr. Biden‘s interview with Special Counsel Robert Hur. The tapes, which were kept private by Attorney General Garland, show that Mr. Biden was not entirely lucid, suffering memory lapses, including a failure to remember the year his oldest son died, as well as repeatedly stumbling over his words. 

In his final report after a probe into claims that Mr. Biden mishandled classified documents, Mr. Hur decided not to press charges, saying, “Mr. Biden would likely present himself to a jury, as he did during our interview of him, as a sympathetic, well-meaning, elderly man with a poor memory.”

Mr. Trump says the newly released tapes disclose a “bigger scandal” about the use of an autopen under the Biden White House. 

“Whoever had control of the ‘AUTOPEN’ is looking to be a bigger and bigger scandal by the moment,” Mr. Trump posted to Truth Social on Friday. In an earlier post on his social media platform, Mr. Trump wrote, “The ‘Pardons’ that Sleepy Joe Biden gave to the Unselect Committee of Political Thugs, and many others, are hereby declared VOID, VACANT, AND OF NO FURTHER FORCE OR EFFECT, because of the fact that they were done by Autopen.”

On Friday, Mr. Comer announced that his committee will open an investigation “into the cover-up of Biden’s mental decline and use of autopen.”

“The American people deserve to know who was actually calling the shots in the Biden White House, because it wasn’t Joe Biden. His mental decline was obvious to anyone paying attention. But instead of being honest, the Biden Administration, Democrats in Congress, and the legacy media lied and covered it up. They gaslit the American people while propping up a man who was unfit to lead,” Mr. Comer said in a press release on Friday, noting that Mr. Garland “defied” a subpoena to release the recordings. 

“Key decisions made in the final days of the Biden presidency, including using autopens to issue blanket pardons for the Biden Crime Family, must be fully examined. There are serious concerns that President Biden lacked the mental capacity to authorize those actions. The American people are done being lied to. We’re going to bring the truth into the light, and starting next week, those involved in the cover-up will begin to be put on notice,” Mr. Comer said in the statement.