The CIA contractors who helped develop and operate the "enhanced interrogation techniques" that the agency used on terror suspects, including waterboarding, were paid more than $80 million, according to the Senate Select Committee on Intelligence report on the CIA's interrogation program released Tuesday.

The contract was for more than $180 million, but the contractors had only received $81 million when their contract was terminated in 2009.

Although the committee identified the contractors via pseudonyms, NBC News has previously identified them as Mitchell, Jessen & Associates, a Spokane, Washington, company run by two psychologists, Dr. John "Bruce" Jessen and Dr. James Mitchell, who had both previously worked with the U.S. Air Force.

The report states that when they were hired the two did not have "specialized knowledge of al Qaeda, a background in counterterrorism or any relevant cultural or linguistic experience."

The CIA made first contact with the psychologists in April 2002, not long after the agency had captured its first major al Qaeda operative, Abu Zubaydah.

"Interrogation wasn't a big deal till we got a big deal guy," said one former intelligence official who spoke with NBC News on condition of anonymity. "We had reporting from prior to 9-11 as well as afterward that Abu Zubaydah might well know about future operations. So … we get him in our clutches…we figure we might need to do something to find out what he knows."

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In late July 2002 the CIA turned to the psychologists, according to both former intelligence officials and congressional investigators. Jessen was then a senior psychologist at the Defense Department agency that taught special operations forces how to resist and endure torture via so called "SERE" training, or Survival, Evasion, Resistance Escape training, at a special "SERE" school. Jessen was sent to the CIA "for several days" to discuss the techniques, according to congressional investigators. Jessen immediately resigned from the Air Force and, along with Mitchell, another recently retired colleague, founded Mitchell, Jessen & Associates.

The business — co-owned by seven individuals, six of whom worked in the SERE program as either employees or contractors — quickly signed a contract with the CIA. In 2006, according to the report, "the value of the CIA's base contract with the company formed by the psychologists with all options exercised was in excess of $180 million." The deal initially provided the two principals with $1,000-a-day tax-free retainers.

The Senate report states the contractor "developed the list of enhanced interrogation techniques and personally conducted interrogations of some of the CIA's most significant detainees using those techniques. The contractors also evaluated whether the detainees' psychological state allowed for continued use of the techniques, even for some detainees they themselves were interrogating or had interrogated."

By 2005, the committee reported, the CIA had turned over all its enhanced interrogation work to the firm.

Within days of hiring Mitchell, Jessen & Associates, the CIA asked the Defense Department for a rush "list of exploitation and interrogation techniques that had been effective against Americans" in the SERE training.

The Pentagon quickly replied with a memo, "Physical Pressures used in Resistance Training and Against American Prisoners and Detainees," say congressional investigators.

Working with Mitchell, Jessen & Associates, the CIA soon developed a menu of 20 enhanced techniques –- a list that was ultimately whittled down to 10, mainly because some of proposed techniques were considered too harsh even for terrorists. The techniques included waterboarding, sleep deprivation and forcing prisoners to assume "stress positions."

John Rizzo, the acting CIA general counsel who met with the psychologists, wrote in his book, "Company Man," that he found some of what Mitchell and Jessen were recommending "sadistic and terrifying." One technique, he wrote, was "so gruesome that the Justice Department later stopped short of approving it."

NBC News has been told by a senior U.S. intelligence official that Mitchell and Jessen had suggested "mock burial," in which a detainee would be led to believe he would be buried alive if he didn't talk. It was not approved.

In Depth

In 2007, according to the Senate report, "the CIA provided a multi-year indemnification agreement to protect the company and its employees from legal liability arising out of the enhanced interrogation program. The CIA has since paid out more than $1 million pursuant to the agreement."

In 2009, the Obama administration terminated the contract. Mitchell, Jessen & Associates had received $81 million at the time of termination.

While the techniques were undeniably harsh, senior CIA officials were comforted by the fact that they had been used by the U.S. against its own servicemen, said the former intelligence official.

A big factor in people's thinking was that these techniques were used in the training of U.S. Special Operations Forces," the ex-official said. "If it was something that had been done to U.S. forces … although admittedly very tough … then it couldn't be considered torture."