A man walks across the seal of the Central Intelligence Agency at the agency’s headquarters. (Alex Wong/Getty Images)

The CIA released dozens of previously classified documents Tuesday that expose disturbing new details of the agency’s treatment of terrorism suspects after the Sept. 11, 2001, attacks, including one who died in Afghanistan in 2002 after being doused with water and chained to a concrete floor as temperatures plunged below freezing.

The files include granular descriptions of the inner workings of the CIA’s “black site” prisons, messages sent to CIA headquarters from field officers who expressed deep misgivings with how detainees were being treated and secret memos raising objections to the roles played by doctors and psychologists in the administration of treatment later condemned as torture.

But the collection also includes documents that were drafted by senior CIA officials to defend the interrogation program as it came under growing scrutiny, including a lengthy memo asserting that the use of often brutal methods had saved thousands of civilian lives.

The 50 documents included in the release were all drawn from records turned over to the Senate Intelligence Committee as part of its multi-year probe of the interrogation program. But while the panel’s 2014 final report includes passages from many of the newly released files, some of the material they contain had not been available to the public until now.

In a press statement, the CIA said it was releasing the files in response to a Freedom of Information Act request. The request, for all documents referred to in the Senate report, was first filed by the ACLU, which said the records “under­score the cruelty of the methods used in its secret, overseas black sites.” The contents were first disclosed in a story on the Vice News website by Jason Leopold.

The disclosures do not fundamentally alter the public understanding of a CIA program that already has been examined in hundreds of news accounts and television documentaries as well as a lengthy executive summary of the full Senate report.

Instead, the new releases add to a small but growing library of publicly available records on a covert program that was among the most controversial in CIA history before it was shut down in 2009.

That controversy was revived last year when GOP Presidential candidate Donald Trump declared that if elected he would order the CIA to resume its use of waterboarding and other harsh interrogation measures — a vow that was denounced by many current and former agency officials.

Among the more unsettling of the newly released files is a detailed internal investigation of the interrogation and death of Gul Rahman, a militant suspected of ties to al-Qaeda who collapsed after being left overnight in a freezing cell at a CIA prison in Afghanistan known as the Salt Pit.

The 35-page file retraces previously reported aspects of the case, including the fact that he had been doused with water and left in a cage with no blankets or heat as temperatures tumbled below 32 degrees. But the declassified chronology exposes the extent to which agency negligence and dysfunction rendered the outcome almost inevitable.

The report describes confusion over who was responsible for medical care of detainees at the Salt Pit and reveals that prisoners were routinely kept in diapers and then stripped of even those when they failed to cooperate.

Rahman was “showing early signs of hypothermia” within days of arrival at the site, according to the report, but was regarded as a defiant adversary who was unlikely to “break” unless subjected to increasingly severe measures.

After an afternoon meal in November 2002, Rahman “threw his plate, water bottle and waste bucket at the guards,” prompting a final and fatal crackdown. He was “shackled in a sitting position on bare concrete while nude from the waist down,” the report said. Patrols noticed him shaking the next morning but didn’t intervene. Two hours later he was found “lying motionless on his right side . . . a small amount of blood coming from his nose and mouth.”

An autopsy concluded that Rahman had likely died of hypothermia because of exposure to the severe cold. Even so, the report found ways to blame Rahman, saying that his “actions contributed to his own death. By throwing his last meal he was unable to provide his body with a source of fuel to keep him warm.”

Other documents expose objections raised by CIA employees to how detainees were handled and whether they ever should have been detained.

The CIA has acknowledged the mistaken arrest in 2004 of Khalid al-Masri, a German citizen who was abducted by police in Macedonia and handed over to the agency. He was transferred by the CIA to the Salt Pit, where interrogators “quickly concluded he was not a terrorist” and had no al-Qaeda connections. “The two Agency officers primarily involved in al-Masri’s rendition justified . . . his continued detention, despite the diminishing rationale, by insisting they knew he was ‘bad,’ ” the report said.

Once the mistake was acknowledged, internal arguments, apparently aimed at avoiding embarrassment, delayed his release for months.

Like the al-Masri case, many of the documents contain familiar outlines of alleged mistreatment, denied and ultimately dismissed by the CIA and law enforcement. Reports on the cases of detainees Abu Hazim al-Libi and Mustafa al-Hawsawi concluded that their alleged waterboarding had instead been only “water dousing,” a procedure that places a detainee on the floor and pours water over his body.

In the Hawsawi case, officials warned that putting him on a board, even if water was not poured on his face, “is just too close to the water board, and if it is continued may lead to problems for us.”

Several of the documents reflect concerns by both CIA and medical officials that they may be held responsible for human rights violations, despite Justice Department opinions saying that certain “enhanced interrogation techniques” are legal. In a May 2005 memo to the CIA Director, Inspector General John L. Helgerson warns that “the opinions are carefully circumscribed and limited to that federal criminal statute prohibiting torture and to the particular circumstances of interrogation as defined by the agency.”

The opinions, he noted, do not address “the possible application” of the international Convention Against Torture, which prohibits “cruel” and “degrading” techniques. “By any common understanding of the term, for example, use of the waterboard may well be ‘cruel.’ Extended detention with no clothing would be considered ‘degrading’ in most cultures, particularly Muslim.”

Helgerson urged the director “to seek further legal guidance” from Justice. In addition, he wrote, “I strongly urge you to restrict, in writing, the current use of interrogation techniques to the specific terms of conditions found to be lawful in the two [Justice] opinions” issued that month, including restrictions of such techniques to 30 days.

A number of the documents in the release are mostly or entirely redacted, including one titled “Anticipated Foreign Reactions to the Public Announcement of the U.S. Secret Terrorist Detention Program” In a memo recounting a Nov. 8, 2006 meeting with the International Committee of the Red Cross, then CIA General Counsel John A. Rizzo notes that “As described to us, albeit in summary form, what the detainees allege actually does not sound that far removed from reality.”

The rest of the 9-page document is redacted.

In one memo, field officers raise “serious reservations with the continued use of enhanced techniques” on Abd al-Rahim al-Nashiri, a suspected al-Qaeda operative still in custody at Guantanamo Bay. The detainee “has been mainly truthful,” the memo said, arguing that continued use of waterboarding and other methods would “push subject over the edge psychologically.”

Despite such concerns among agency operatives, top officials at headquarters defended the program as effective. A 2004 memo to the CIA’s inspector general by James L. Pavitt, who at that time was deputy director for operations, said he welcomed an internal probe because he was convinced it would confirm the agency’s “fundamental respect for human values.”

Pavitt urged the inspector to be aggressive in his inquiry and not “shy away from the conclusion that our efforts have thwarted attacks and saved lives.” Enhanced techniques “including the water board have been indispensable to our successes.”