The alleged mastermind of the 9/11 attacks, like the Senate intelligence panel's Democrats, has come out against President Donald Trump's nomination of Gina Haspel to lead the CIA.

Both Khalid Sheikh Mohammed and the Democrats question whether Haspel, a longtime CIA agent, is fit to run the agency given her involvement in the torture of prisoners following the attacks in 2001.

Haspel is due to appear Wednesday before the Senate Intelligence Committee for her confirmation hearing.

The Al-Qaeda leader, who was captured in March 2003 and was reportedly tortured, asked a military judge Monday at the U.S. prison in Guantanamo Bay, Cuba, to share an attachment titled "Additional Facts, Law and Argument in Support" with the intelligence committee, the New York Times reported.

The attachment contains "six specific paragraphs of information" regarding Haspel and was written by Mohammed himself. Marine Lt. Col. Derek A. Poteet, one of Mohammed's lawyers, claims his legal team believes the information is important.

“I am not able to describe the information,” he said, noting that the information came from the detainee himself and not from files turned over by the government to the defense lawyers regarding Mohammed's treatment in the CIA custody.

Multiple Democrats have criticized Haspel's nomination, with U.S. Sen. Jon Tester of Montana saying he opposes her because he objects to waterboarding, a controversial enhanced interrogation technique deemed torture by many opponents.

Four Democrats on the Senate Intelligence Committee -- Kamala Harris and Dianne Feinstein, both of California; Ron Wyden of Oregon; and Martin Heinrich of New Mexico -- also asked to declassify all CIA information regarding Haspel's role in the program.

“The American people deserve transparency regarding the background of a nominee who will be asked to represent them, and their values, around the world,” they wrote in a letter to Daniel Coats, director of national intelligence. “Without making this information available to the American people, Ms. Haspel’s nomination cannot be fully and properly considered by the Senate.”

Haspel in 2002 was a chief of base at a black-site prison in Thailand, where detainees were subjected to harsh interrogation, including waterboarding.

Some outlets have accused Haspel of taking part in the waterboarding of Abu Zubaydah, an alleged Al-Qaeda terrorist. News site ProPublica, originator of the allegations, has since retracted the article, saying Haspel arrived to the base after the interrogation of Zubaydah ended.

It remained unclear if Mohammed, who was detained at sites in Afghanistan and Poland before arriving at Guantanamo bay, was at any point under supervision of Haspel. The recently declassified timeline of her clandestine career hasn't specified if she worked in those countries.

The Associated Press contributed to this report.