Washington (AFP) – CIA interrogators sought a truth serum to use on Al-Qaeda prisoners in addition to waterboarding and other torture techniques after the September 11, 2001 attacks, according to formerly top secret documents released Tuesday.

Desperate to get information about possible future attacks from Abu Zubaydah, who was believed to have helped plot the 9/11 attacks, interrogators reached back decades to the agency’s 1950s experiments with mind-altering drugs like LSD and also to Russian testing of alleged truth serums in the 1980s.

In “Project Medication,” the CIA doctors weighed barbiturates like sodium amytal and psychotomimetics, which create symptoms of psychosis. They were particularly interested in a drug trade-named Versed, or midazolam, a sedative that can cause loss of memory while in effect.

The idea came to officials of the CIA’s Office of Medical Services (OMS) amid frustration that Abu Zubaydah “showed remarkable resilience” despite being put through vicious treatment, including stress positions and sleep deprivation.

“The intensity and duration of AZ’s interrogation came as a surprise to OMS and prompted further study of the seemingly more benign alternative of drug-based interviews,” said the report.

But they found an absolute lack of historical evidence that drugs could induce a subject to give up information.

“No such magic brew as the popular notion of truth serum exists,” said a 1961 intelligence review.

“It seems likely that any individual who can withstand ordinary intensive interrogation can hold out in narcosis,” it said.

Still, the interrogators considered the drugs could trick a prisoner into thinking that he had done so.

“Such drugs, although widely regarded as unreliable sources of ‘truth,’ were believed potentially useful as an ‘excuse’ that would allow the subject to be more forthcoming while still saving face,” the interrogators reasoned.

But they faced a prohibition on agency medical research on prisoners that came after the agency’s 1950s MKULTRA program in which mind-altering drugs were tested on humans. One man who was secretly given LSD in that program subsequently committed suicide.

After having stretched legal limits to get permission to use torture techniques on prisoners, the CIA’s legal office “did not want to raise another issue with the Department of Justice,” the report said.

The 90 page report on the OMS record in post 9/11 interrogations was released after a court battle led by the American Civil Liberties Union.

The ACLU said the entire report showed how medical doctors were critical to the torture program and helped legitimize it.

“One of the most important lessons of the CIA’s torture program is the way it corrupted virtually every individual and institution associated with it,” said ACLU attorney Dror Ladin.