The United States will soon release a long-awaited report detailing the findings of a Senate investigation into the CIA’s use of enhanced interrogation techniques, and sources now say those tactics far exceeded what the world was led to believe.

According to an article published on Sunday by the UK’s Telegraph, the American intelligence officers tasked with interrogating alleged Al-Qaeda members and other terror suspects in the wake of the September 11, 2001, attacks didn’t just waterboard detainees — they nearly killed them.

“They weren’t just pouring water over their heads or over a cloth,” a source described by the Telegraph as having first-hand knowledge of the post-9/11 period when the tactics were used told the paper. “They were holding them under water until the point of death, with a doctor present to make sure they did not go too far.”

“This was real torture,” the individual added.

Telegraph reporter Peter Foster wrote from Washington that a second source with knowledge of the investigation said the eventual release of the 3,600-page Senate Intelligence Committee report will likely “deeply shock” the general public because it contains accounts of interrogation techniques far worse than what has already been revealed.

“They got medieval on his ass, and far more so than people realize,” one source told the Telegraph with regards to the tactics used on two CIA detainees — alleged 9/11 mastermind Khalid Sheikh Mohammed and supposed USS Cole bomber Abd al Rahim al Nashiri — borrowing a line from the Quentin Tarantino film “Pulp Fiction” to describe the torture tactics expected to be included in the Senate report.

For now, however, the release of that long awaited investigation remains up in the air: although the Senate committee tasked with investigating the intelligence agency’s use of interrogation tactics has long since completed their study, other divisions of the federal government continue to conduct redactions ahead of the report’s eventual release. Separately, allegations of spying made by both the head of that committee and the director of the CIA against one another have further complicated the completion of the report, of which only a fraction — 700 pages at most, according to The Guardian — will be made public.

“Given the lengths that Bush-era CIA officials went to cover up the truth, including destroying videotapes depicting waterboarding of prisoners, it comes as no surprise that the torture was more brutal than previously revealed,” Open Society Justice Initiative attorney Amrit Singh told the Telegraph this week, “It is, however, something that the American public has a right to know about, and an obligation to reckon with, and these revelations only underscore the urgent need for release of the Senate Intelligence Committee report.”

Sen. Dianne Feinstein (D-California), the chairperson of the intelligence committee, said during an unaired segment of a recent “Meet the Press” interview that she expects the executive summary of the so-called torture report to be ready for the public by the end of September.

“What we are engaged in is working with the administration to see that the redaction is such that it does not destroy the report,” Feinstein said. “If you redact the evidence — heavily — then we cannot sustain our findings. We will not put out a report that does not enable us to sustain our findings. And I believe that that is understood.”

“Progress has been made. I think the report will likely come out in the second half of September sometime — but it won’t come out until it is readable and understandable,” added the senator.