A man who published a study that he said proved the Nazis did not gas Jews at Auschwitz was deported from the United States to his native Germany to serve a prison term for Holocaust denial.

Germar Rudolf, also known as Germar Scheerer, had his emergency petition to block the deportation rejected by the U.S. Supreme Court on Thursday. He was put on a flight in Chicago on Monday night and arrived in Germany on Tuesday.

Rudolf, a chemistry graduate of Bonn University and a former student at Max Planck Institute in Stuttgart, was sentenced in 1995 to 14 months in prison for Holocaust denial, a crime in Germany, but then disappeared.

He petitioned the Supreme Court because he was appealing his deportation to the 11th U.S. Circuit Court of Appeals in Atlanta, but the next hearing was not scheduled until January - too late to halt the action.

Rudolf's "Expert Report on the Formation and Detectability of Cyanide Compounds in the Gas Chambers' of Auschwitz" concluded that "no mass gassings with hydrogen cyanide took place in the National Socialist concentration camp Auschwitz."

In sentencing Rudolf, the Stuttgart court cited his "incitement of the people in conjunction with denigration of the memory of the dead, libel and incitement to racial hatred."

Some 1.5 million people, most of them Jews, were killed at Auschwitz and the nearby Birkenau in Nazi-occupied Poland during World War II.