Al-Qahtani's case, experts say, stands as a litmus test for whether President Joe Biden is committed to his pledge to shutter the controversial facility -- an enduring symbol of the George W. Bush administration's global "war on terror" that persisted through the Barack Obama and Donald Trump presidencies. And, they say, the case has troubling implications for the humane treatment of other prisoners of war, including any US servicemembers who may be captured in future conflicts.

The challenge facing the Biden administration's legal team is how to balance the merits of al-Qahtani's case with the larger political realities at play, said Stephen I. Vladeck, a professor at the University of Texas School of Law who follows Guantanamo litigation. While there will be those who urge the President to side with the severely mentally ill detainee as part of the process of closing down Guantanamo, said Vladeck, others within the White House may advise Biden to consider the political drawbacks of any decision that may help set free a man who allegedly aspired to take part in the worst terrorist attack on US soil.

"As much as the administration may wish to show compassion toward al-Qahtani, any broader effort to effectuate his release and that of the other 38 men still in detention there would require political capital that the administration is either unable or unwilling to spend," said Vladeck, who is a CNN legal analyst.

Efforts to keep al-Qahtani in custody, however, have their own potential downsides. Biden has staked his foreign policy agenda on improving relations with US allies and changing America's image abroad. He has sold his decisions to end combat missions in Afghanistan and Iraq as moving the country forward from the perpetual "war on terror" footing it has operated on for nearly two decades. Keeping al-Qahtani in custody and Guantanamo open would not align with those stated goals, said Eric M. Freedman, a professor of constitutional law at Hofstra University who has long been critical of detentions at Guantanamo.

"The saga of this individual clearly exemplifies the layer upon layer of outrage that the entire Guantanamo venture has represented since its inception," Freedman said. "If President Biden wants to adhere to his campaign promises to bring America back, freeing this man would be an excellent place to start."

Mental illness, extremism and capture

Al-Qahtani's long history of mental illness began at age eight when he was in a serious car accident and thrown from the vehicle, suffering a traumatic brain injury, according to Dr. Emily Keram, a court-appointed psychiatrist hired at the request of defense attorneys to evaluate their client. Keram, who reviewed al-Qahtani's Saudi medical records, said the injury impaired his ability to read and concentrate, which worsened with two more car accidents in later years.

In the years that followed, al-Qahtani experienced "episodes of extreme behavioral dyscontrol," according to Keram, who has interviewed al-Qahtani multiple times, including during two trips to Guantanamo Bay, since 2015. She also interviewed an older brother of al-Qahtani, one of 12 children in his family.

At some point in his early 20s, al-Qahtani was found by Riyadh police naked in a garbage dumpster, Keram noted in her report. A few years later, police in the holy city of Mecca arrested al-Qahtani after he hurled himself into oncoming traffic, Keram said.

That incident resulted in his involuntary commitment to the psychiatric unit of the city's King Abdul Aziz Hospital for four days where doctors determined he was delusional and suicidal, according to Keram, who also said he suffered from schizophrenia prior to entering US custody.

Six months after leaving King Abdul Aziz Hospital, al-Qahtani started embracing a more extreme version of Islam and later attended an al-Qaeda training camp in Afghanistan, US authorities allege.

Al-Qahtani's "psychological and cognitive deficits would be recognized by others, leading him to be vulnerable to manipulation and coercion," Keram wrote in a June 2016 assessment of al-Qahtani.

At the camp, according to US military records, al-Qahtani met al-Qaeda leader Osama bin Laden and swore his loyalty to him. Bin Laden personally selected him to take part in the 9/11 attacks, the records claim.

On August 4, 2001, al-Qahtani landed in Orlando, Florida, with a one-way ticket and $4,000 in cash, which made immigration officials suspicious. They questioned him for 90 minutes before sending him back to Dubai. While military records allege that he was in Orlando to meet al-Qaeda member Mohamed Atta, one of the September 11 hijackers, they also note that al-Qahtani later told interrogators he didn't know the purpose of the meet up. By the end of that month, al-Qahtani had returned to Afghanistan.

Weeks later, in the wake of the September 11 attacks, the Bush administration embarked on a global manhunt to find the perpetrators that extended to the far reaches of Afghanistan's remote eastern frontier.

In December, as al-Qahtani traveled with other suspected al-Qaeda fighters from remote Tora Bora in eastern Afghanistan to cross into Pakistan, he was captured by the Pakistani army at the border and transferred to US custody roughly two weeks later, military records show.

Washington moved al-Qahtani to Guantanamo Bay on February 13, 2002, one of the first wave of detainees that arrived at the new facility.

He became known as Detainee 063.

Military dogs, strangling and beatings

For approximately 39 hours in May 2015, Keram met with al‐Qahtani in a bare interrogation room at Camp Echo, a former CIA black site in the Guantanamo Bay Detention Camp.

She was there to evaluate the overall state of his mental health after more than 13 years of detention and whether he was receiving adequate medical and psychiatric care.

When their conversations turned to his torture at Guantanamo, al-Qahtani often wept as he relived the ordeal.

According to the government's interrogation logs, which describe the torture in detail and were leaked to Time Magazine in 2005, al-Qahtani experienced some of the most severe "enhanced interrogation" techniques approved by former Defense Secretary Donald Rumsfeld under his authorized "First Special Interrogation Plan." Rumsfeld infamously scribbled a note in the margins of a memo suggesting even harsher techniques.

Over a roughly 50-day period between November 2002 and January 2003, al-Qahtani was subjected to a long list of brutal methods -- including sleep deprivation, extreme temperature and noise exposure, sexual humiliation, beatings and strangling, according to Keram's report. At times, in apparent protest at his treatment, al-Qahtani refused to eat or drink water.

Dehydrated, doctors would occasionally forcibly administer an IV, the logs show. In one instance, al-Qahtani bit an IV tube in two before he was restrained.

Al-Qahtani's interrogators also threatened him with military dogs and tied a leash to his shackles, led him around the room and forced him to perform a series of dog tricks. At times, they would not allow him to use the bathroom, resulting in him urinating on himself repeatedly, according to military records.

Al-Qahtani told Keram that during his torture he experienced hallucinatory episodes. In one, he believed he was dead and seeing ghosts before an imaginary bird assured him that he was still alive. He told her that he wanted to end his life to stop the torture.

"The intensity I had to kill myself was not the intensity to die, it was the intensity to stop the psychological torture, the horrible pain of solitary confinement," said al-Qahtani. "The symptoms of psychological torture were horrific. It was even worse than the effects of the physical torture."

During the sessions, interrogators allowed medical personnel inside the room to check al-Qahtani's vitals signs -- sometimes three times a day. They were done to ensure he was "able to continue" with the interrogations, the records note.

He was hospitalized on two occasions for an abnormally slow heart rate, according to military records. In one instance, officials flew in a radiologist from a naval station in Puerto Rico to read al-Qahtani's CT scan after his heart rate dropped to 35 beats per minute. When the doctor found "no anomalies" al-Qahtani was "hooded, shackled and restrained in a litter" and taken back to Camp X-Ray for interrogations the following day, the logs report.

On December 6, 2002 -- roughly two weeks after the interrogations began -- al-Qahtani told interrogators the story that he had met bin Laden in Afghanistan. "I am doing this to get out of here," he said. He retracted the story the next day, saying that he had made the claim because he was under pressure.

In an October 2008 memo, a military official alleged that al-Qahtani's admission of involvement in bin Laden's "special mission to the US appear to be true and are corroborated in reporting from other sources." The document does not detail what information the military had or how it was corroborated.

In the June 2016 evaluation, Keram concluded that al-Qahtani could not receive effective mental health treatment while he remains imprisoned at Guantanamo. She recommended his release to Saudi Arabia, where the government has said it would provide him psychiatric care.

"The profound physical and psychological torture Mr. al-Qahtani experienced during interrogations, coupled with his inability to control what was happening to him, led him to conclude that he had only two means of ending his suffering; suicide or compliance," wrote Keram of the torture sessions. "Thus, Mr. al-Qahtani's statements were coerced and not voluntary, reliable, or credible."

Al-Qahtani's condition has significantly deteriorated in the last year. He has tried to take his own life on three separate occasions in the last nine months during psychotic episodes driven by schizophrenic hallucinations, including by swallowing broken pieces of glass, his legal team says.

"The fact that somebody as sick as Mr. al-Qahtani poses some kind of security threat to the United States is unthinkable," said Scott Roehm, Washington director for The Center for Victims of Torture, a nonprofit that has pressured the Biden administration to close Guantanamo.

CNN was unable to interview al-Qahtani for this article.

This past February, Keram supplied another court declaration, writing that al-Qahtani was at "high risk for suicide."

Court ruling forces Biden White House to make decisions

To probe the last 16 years of court records in al-Qahtani's legal quest for freedom -- a cache of more than 400 filings between October 2005 and June 2021 -- is to take a journey through some of the most sordid moments in the recent history of the United States.

The government dropped all charges against him in 2008, which Susan Crawford, a senior Bush administration official later admitted to The Washington Post was because he was tortured. Crawford served as the head of military commissions at Guantanamo Bay and was charged with deciding whether to bring detainees to trial. Any information gleaned during those sessions at Camp X-Ray, Crawford acknowledged, was inadmissible in court.

The admission was unprecedented.

Despite dropping the charges, the 2008 military memo argued for al-Qahtani's continued detention, categorizing him as a "high-risk" to national security.

Al-Qahtani's legal team has made numerous efforts to secure his release, particularly after 2008 when charges against him were dropped. All were unsuccessful.

In the face of those defeats, al-Qahtani's lawyers decided in April 2017 to go down an untried legal route for Guantanamo detainees. As a prisoner of war, they argued, their client had the right under the Geneva Conventions to be granted a medical evaluation by an independent panel of three doctors, known as a mixed medical commission.

Al-Qahtani's lawyers argued that an independent medical evaluation was guaranteed under a US Army rule known as Army Reg. 190-8, a domestic law which allows for the repatriation of sick and wounded prisoners of war.

The strategy, according to al-Qahtani's lawyers, was to see if other doctors agreed with Keram's view that al-Qahtani was so mentally ill that he poses no threat to the United States and should be repatriated to Saudi Arabia. Justice Department lawyers contended that the Army rule did not apply to Guantanamo detainees.

After years of disappointment, al-Qahtani and his legal team had its first significant victory. In March 2020, US District Court Judge Rosemary Collyer, in a 25-page opinion, ordered the US military to permit a mixed medical commission to examine al-Qahtani and determine his eligibility for repatriation to Saudi Arabia for psychiatric care.

The judge's order shook the Pentagon, which has consistently fought to block civilian courts from deciding the fate of Guantanamo detainees. The Trump administration appealed the order, which the DC Court of Appeals dismissed in September.

A Pentagon spokesperson declined to comment for this article, citing al-Qahtani's ongoing case.

On January 15, in the waning days of Trump's presidential term, the Justice Department made another bid to have Collyer's ruling tossed out, filing a "motion for reconsideration" in the US District Court for the District of Columbia, citing a last-minute rule change instituted by then-Army Secretary Ryan McCarthy declaring Guantanamo detainees exempt from Army Reg. 190-8. The new rule, the government said, made the judge's ruling moot.

"In the final hours of the Trump administration, they tried to move the goal posts," said Ramzi Kassem, a City University of New York law professor whose legal clinic represents al-Qahtani with The Center for Constitutional Rights. "It's the government, having lost under the law, then trying to change the law."

In the back-and-forth of court filings, al-Qahtani's attorneys have argued that the last-minute attempted rule change didn't change the government's obligation to adhere to the Geneva conventions.

The Biden administration has now inherited the case and has on five occasions asked the court for an extension as it determines how it will proceed. It has until September 8 to decide which course of action to take: Continue to fight Collyer's order, grant a mixed medical commission access to al-Qahtani, or drop the matter and repatriate him to Saudi Arabia.

Wherever the White house falls, the potential moral, ethical and practical implications are significant.

The White House declined comment on al-Qahtani's case, citing the pending litigation.

If the Biden White House were to allow a mixed medical commission to examine al-Qahtani at Guantanamo, the first in the base's history, he could set a precedent in which a number of other prisoners could request independent medical evaluations that could expose the conditions they have been subjected to for nearly two decades in some cases. If the government denies al-Qahtani a medical evaluation, however, and supports the Trump administration's attempted unilateral carve out to exclude Guantanamo detainees from the Geneva Conventions, that could put US servicemembers captured as prisoners of war in peril. In a life-or-death scenario, those servicemembers could be denied the same type of treatment and medical evaluations al-Qahtani is now seeking, said Freedman.

Looming in the background is the fierce debate over whether Guantanamo detainees are entitled to "due process rights," a constitutional guarantee to fair treatment in court that is a bedrock of the American judicial system. Previous administrations have argued that such rights do not apply to them. The Biden administration's legal team is divided on the issue, according to a recent New York Times report. The administration has yet to take a public stance on the matter.

Recently, however, the Biden White House put its first stamp on Guantanamo policy on July 19, allowing the transfer of detainee, Abdul Latif Nasser, to Morocco. Because Nasser -- who was never charged with a crime -- had been cleared for repatriation in 2016, it's unclear whether or not the move represents a significant shift in policy.

Meanwhile, as the battle over the future of Guantanamo Bay plays out in Washington, al-Qahtani spends his days in isolation in his cell. He avoids other detainees because of his schizophrenic outbreaks, Keram noted in an August 2020 court declaration.

In a recent phone conversation with his lawyer, Kassem, al-Qahtani said he survived on the hope of seeing his family again. The unclassified notes of that call, according to Kassem, reveal the desperation his client feels.

"There is no life for me here," al-Qahtani told his attorney. "If I have a future, it is outside this place."