A few years ago, I was talking with a Washington psychiatrist, a Harvard Medical School graduate whom I’ve known and respected for more than 20 years. When, for some reason, our past military service came up, I remembered he’d been in the Air Force during the Vietnam War, but couldn’t recall where he’d been stationed.

“At Andrews,” he said, meaning the air base just outside Washington. “Treating PTSD,” he added — post-traumatic stress disorder.

Vietnam combat veterans, I assumed.

“No,” he said. “Russia.”

No way.

But in the late 1960s, my friend insisted, he’d treated men who said they had been dispatched to Siberia on clandestine reconnaissance operations.

Their mission: to hunker down deep in the forests for weeks at a time with telemetry equipment to monitor Soviet ballistic missile tests.

This was sometime in the very early ’60s, supposedly, a brief period between the end of U-2 overflights and the deployment of spy-in-the-sky satellites.

My friend said his patients described training with drugs and other mind-control techniques to perform the mission — then forget them, like the Manchurian Candidate.

But now they were remembering fragments, they told him, giving them terrifying nightmares about things they could not quite believe they had done.

They thought they were losing their minds. So did any loved ones who they dared tell their looney-sounding tunes to.

But this being America, of course, they — and other self-described victims of CIA mind control experiments — formed self-help groups. And for several years, it turns out, they have been holding yearly conferences, like one just outside Hartford, Conn., next month.

“About a hundred” people usually show up, says Neil Brick , coordinator of “The Eleventh Annual Ritual Abuse, Secretive Organizations and Mind Control Conference.”

Brick, 49, told me that he, too, has “recovered memories of being part of experimental situations — being given to people to go on missions” under the CIA’s mind control experiments program, code-named MKULTRA.

MKULTRA did, in fact, exist. It is described in the CIA’s own internal documents, 16,000 pages worth obtained by John Marks for his ground-breaking 1979 book, “The Search for the Manchurian Candidate: The CIA and Mind Control.”

One was an “eyes-only” report on MKULTRA by the CIA’s inspector general, in 1963, which said “there have been major accomplishments both in research and operational employment.”

“Operational employment” would seem to say the zombies were created and dispatched, with great results.

The late Sidney Gottlieb, who ran MKULTRA , also described the program, which began in the early 1950s and continued at least into the late 1960s, in congressional testimony in 1977.

On the other hand, much remains unknown. CIA Director Richard M. Helms ordered the destruction of boxes upon boxes of documents, including the treatment records of unknown numbers of “patients” agency “doctors” experimented on in psychiatric hospitals (including a wing of Georgetown University Medical Center), and secret locations, including military bases.

So its alledged victims have no records to back up their stories. Books by self-described MKULTRA survivors tend to get thrown into the UFO bin.

Neil Brick grants there’s a stigma that comes from going public with such X-Files-type stories, asking, for example, that I not print his location or occupation.

It’s a conundrum of the first order, isn’t it?

We have extensive documentation of the CIA’s Manchurian Candidate experiments, but when the Manchurian Candidate himself walks up to tell his story, most people shake their heads or laugh.

Brick admits that “some people” attending his past conferences “have psychiatric issues,” but he says he believes “the majority are survivors of MKULTRA.”

For years, of course, the CIA laughed off rumors of drug experiments.

Today, the agency and the Pentagon stoutly deny they have used hallucinogenic and other mind-altering drugs on prisoners at Guantanamo and secret sites elsewhere.

Just as in the 1970s, however, as I wrote in April, evidence to the contrary is mounting.

The Washington Post’s Joby Warrick also tracked down former prisoners at Guantanamo who said their minds were destabilized by repeated drug injections.

Such stories have been told for 40 years now.

Who are you going to believe?

Jeff Stein can be reached at jstein@cq.com.