Former Democratic president Bill Clinton once praised a Holocaust denier for “keeping the memory and the lessons of the Holocaust alive.”

But it’s highly unlikely that Clinton even knew the man he praised was actually an undercover Holocaust denier using an assumed identity.

“It is with great pride that I recognize David Stein and his organization, the Tinbergen Archives, for their part in keeping the memory and the lessons of the Holocaust from ever being forgotten,” Clinton said in a 1998 commendation letter to filmmaker David Stein for one of his Holocaust documentaries.

But “David Stein” was actually an undercover “Holocaust revisionist” named David Cole, who gained notoriety in the early 1990’s with appearances on television programs like “Montel Williams” and “Donahue.”

Cole made the Holocaust revisionism documentary, “David Cole Interviews Dr. Franciszek Piper: A Jewish Researcher’s Honest Look at WWII and Auschwitz.” After several years of media attention, Cole changed his name in the mid-’90s to “David Stein” and moved to Hollywood to produce non-revisionist Holocaust documentaries, saying, “I gave mainstream audiences what they wanted.” (RELATED: Democratic Congresswoman Praised David Cole — Well Before He Changed His Name).

When “Stein” was exposed as Cole by The Guardian in 2013, he said that he still doubted some official historical details about the use of gas chambers in the Holocaust.

Reached for comment by The Daily Caller, Cole said that the Clinton commendation letter was obtained for his organization by a politically-connected lawyer named Herbert Feiler, who supported “Stein’s” work.

“Herbert was a really nice guy but i can’t make any real independent verification because at the time when that was sent to me it didn’t matter,” Cole told TheDC, noting that factual accuracy was not his main concern during the period in which he was undercover. “I was David Stein doing work that was very very mainstream holocaust work…it wasn’t completely unthinkable that it could have been praised in one of the holocaust commemoration day ceremonies or weeks.”

Feiler has since died. Cole continues to live in Los Angeles, where he is selling a book about his years as an undercover Hollywood gadfly. A request for comment from Clinton was not returned.

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