Michel Thomas, who died Saturday at his Manhattan home at age 90, was a World War II hero and a language teacher to the stars who claimed that his pricey three-day seminars could impart as much French or German as the same number of years of college courses.

His wartime exploits were astounding. They included escaping slave labor camps and surviving interrogation by the infamous Klaus Barbie; committing sabotage with the French Resistance and then capturing and interrogating hundreds of Nazis as a member of the American Counter-Intelligence Corps; being present at the liberation of Dachau, and preserving several tons of Nazi identification documents.

Thomas then settled in California, where he tutored stars like Grace Kelly and Yves Montand and once took part in early LSD experiments with Aldous Huxley’s wife. In later years, he gained notoriety for his testimony in the 1987 trial of Barbie, known as the “Butcher of Lyon.” Thomas recounted how he feigned ignorance of German while Barbie instructed one of Thomas’s interrogators to shoot him in the head.

Thomas’s biographer, the British journalist Christopher Robbins, quoted a linguist colleague as saying, “Either more miracles are associated with your life than anyone I could possibly imagine, or you’re the biggest charlatan who ever walked the face of the earth.”

The Los Angeles Times suspected the latter, and in 2001 the paper published a critical review of the biography’s claims. Without drawing explicit conclusions, the article stated, “Many of his claims are impossible to prove – or disprove. Nevertheless, they have frequently propelled him into the public eye.”

Thomas sued the Times for defamation, unsuccessfully. The publicity garnered by the case caused veterans of his Army unit to come forward and confirm some of his claims. Others were verified by archival documents.

In May 2004, the Army belatedly presented Thomas with a Silver Star that he had been nominated for in 1944.

The Times’s editor, John Carroll, continued to label Thomas’s story “preposterous.” He added, “If you read this … biography, you’d be amazed you’d never heard of this man, because he pretty much single-handedly won World War II for us.”

This was overstatement, but there’s no doubt Thomas played a significant part in it.

Thomas was born Moniek Kroskof in Lodz, Poland. His family was prosperous Jewish clothing and textile merchants. When anti-Semitism became intense, he was sent to live with an aunt in Breslau, Germany, and then to study linguistics in France. After the Germans invaded, Thomas, by then living near Nice and organizing floor shows at resorts on the Cote d’Azur, was arrested frequently.

In the biography, “Test of Courage,” Thomas said his prowess as a lover initially helped protect him from capture. (“And as we were making love … an American artillery position opened fire right above us in the hills.”) He ended up working as a slave laborer in a mine near Aix-en-Provence, then in a lumber camp in the Alps.

After escaping just before being transported to Auschwitz, Thomas said he joined the Resistance and was again captured and interrogated by Barbie, whom Thomas convinced that he was a French artist. He said he helped the Resistance destroy phone lines in anticipation of D-Day. Michel Thomas was one of several noms de guerre he employed at the time.

In 1944, Thomas joined up with the U.S. Army’s 45th Infantry Division, where he led reconnaissance patrols that became part of his Silver Star citation. “Lt. Thomas was instrumental in capturing many enemy prisoners whom he personally interrogated and obtained much vital information,” the citation read. Thomas’s linguistic ability – he eventually claimed fluency in 11 languages – was key to his survival and success.

In 1945, according to the Army News Service, Thomas joined the Counter Intelligence Corps, and in May he participated in the liberation of Dachau. According to Thomas and various archival documents, he arrested and interrogated the camp’s commander, Emil Mahl, known as the Hangman of Dachau.

Thomas subsequently uncovered a cache of Nazi documents; participated in tracking down and arresting a German major implicated in the massacre of 130 American soldiers in the Battle of the Bulge, and became involved in undercover operations that exposed covert Nazis after the end of the war.

In 1947, Thomas moved to California, where he opened the first of his language centers, initially called the “Polyglot Institute.” He later changed the name because “nobody seemed to know what polyglot meant.” Eventually Thomas opened centers in Beverly Hills, London, and New York. Among his celebrity clients were Kim Novak, Johnny Carson, Bob Dylan, and Cardinal O’Connor, and his corporate Web site includes testimonials from Woody Allen, Emma Thompson, and Ann-Margret.

Thomas claimed he based his system on a process of breaking down language into small constituent units but was otherwise cagey about exactly how the system worked. It was important that students be relaxed when learning. “English is French, badly pronounced,” he told a reporter from the Daily News.

He claimed that wartime experiences had hardened him mentally to pain and improved his memory greatly. He certainly remembered more spectacular stories than could be verified: for instance, traveling with Arab camel caravans as a teenager and winning a small fortune at the slots at Monte Carlo in 1941.

In his biography, Thomas compared his wartime heroics to sitting at a gambling table. “I felt like a gambler … on a long winning streak. You are only cautious with the original stake. … That is how I felt with my life. … It was a part of my winnings from the camps and the Resistance.”

Starting in the 1960s, Thomas volunteered his time with disadvantaged students in Los Angeles, and later in London. In 1977 he married a Los Angeles schoolteacher; they subsequently divorced.

He was a frequent speaker at the Renaissance Weekend gatherings in Charleston, N.C., and attended the most recent one during the New Year’s holiday. His talks, organizers said, were titled, “What’s the Story? – Surprising Insights from Walks through History” and “If These Were My Last Remarks.”

Michel Thomas

Born Moniek Kroskof February 3, 1914, at Lodz, Poland; died January 8 at Manhattan of heart failure; survived by his children, Micheline and Gurion; a stepson, Mike Schmidt, and his ex-wife, Alice Burns.