The Justice Department is launching an investigation into former President Biden's pardons and use of autopen, according to a report.

Reuters reviewed an email sent by U.S. pardon attorney Ed Martin on Monday, in which he wrote that the investigation involves whether Biden "was competent and whether others were taking advantage of him through use of AutoPen or other means."

Trump has claimed that Biden used autopen for pardons and did not sign the pardons or know anything about them.

It is unknown whether Biden used autopen on pardons. However, the Oversight Project, an investigative arm of the conservative Heritage Foundation, alleged excessive use of autopen signature by Biden when he was in the White House.

"We gathered every document we could find with Biden's signature over the course of his presidency. All used the same autopen signature except for the announcement that the former President was dropping out of the race last year," the Oversight Project said in March. The organization questioned "who controlled the autopen" because "they controlled the presidency."

Martin's email said the investigation's focus is on Biden's preemptive pardons to several family members and clemency to 37 federal inmates, giving them life in prison sentences instead of the death penalty.

On Biden's last day in office, he pardoned his brother Jim, his sister-in-law Sara, his sister Valerie and her husband, John Owens, his brother Francis, Dr. Anthony Fauci, retired Gen. Mark Milley, and members of the House Jan. 6 committee.

Last month, Martin told ABC News, "I do think that the Biden pardons need some scrutiny. And they need scrutiny because we want pardons to matter and to be accepted and to be something that's used correctly. So I do think we're going to take a hard look at how they went and what they did.

"If they're null and void, I'm not sure how that operates, but I can tell you we've had already, I've had in my current position, or my position as US Attorney, we had been taking a look at some of the conduct surrounding the pardons and the Biden White House."

He added that he doesn't believe that Biden's use of "auto-pen" for pardons is a problem, despite Trump suggesting that it makes them invalid.