Detainees inside the US military prison at Guantanamo Bay were forcibly injected with powerful “mind altering drugs” and then interrogated, according to a declassified report obtained by Truthout through a Freedom of Information Act Request.

Some of the drugs, which included intoxicating anti-psychotic sedatives, “could impair an individual’s ability to provide accurate information,” according to the report written by the Pentagon’s inspector general.

The detainees were often not told what medications they were receiving and a number of them were deliberately tricked into believing they had been drugged with “truth serum,” in what Truthout calls “a form of psychological manipulation.”

Since the establishment of the due-process-free Guantanamo prison, there have been many allegations from current and former detainees and their civilian and military attorneys that detainees were forcibly drugged prior to and during interrogations. But the declassified report confirms it and provides a detailed account.

The Pentagon’s inspector general said in the report that he was unable to confirm whether or not detainees were drugged “to facilitate interrogation” as a matter of government policy. But the findings nevertheless expose additional abuses suffered by detainees at the infamous military prison.

The report also found that “certain detainees, diagnosed as having serious mental health conditions being treated with psychoactive medications on a continuing basis, were interrogated.”

“The inspector general’s report confirms that detainees whose mental deterioration and suffering was so great as to lead to psychosis and attempts at self-harm were given anti-psychotic medication and subjected to further interrogation,” Leonard Rubenstein, a medical ethicist at Johns Hopkins Center for Public Health and Human Rights told Truthout.

“The problem is not simply what the report implies, that good information is unlikely to be obtained when someone shows psychotic symptoms, but the continued use of highly abusive interrogation methods against men who are suffering from grave mental deterioration that may have been caused by those very same methods,” Rubenstein said.