Berlin ? Leni Riefenstahl, who made masterful films for the Nazis, turned 100 Thursday with a birthday party at a lakeside hotel and a fresh criminal investigation into whether she broke German law prohibiting Holocaust denial.

The probe was prompted by a Gypsy organization’s claim that Riefenstahl used slave laborers from concentration camps as extras in her film “Lowlands.”

The accusation by the Cologne-based organization Rom said Riefenstahl used 120 Gypsies from camps in Salzburg and Berlin from 1940 to 1942, then failed to prevent them from being returned to the Nazi camp system, where many died.

The group accuses Riefenstahl of Holocaust denial for dismissing those allegations as nonsense in an April interview published in the Frankfurter Rundschau newspaper.

“We saw all the Gypsies that played in ‘Lowlands’ again after the war,” Riefenstahl was quoted as saying. “Nothing happened to them.”

Iris Pinkepank, spokeswoman for Rom, said her organization could prove many of those Gypsies died by comparing Riefenstahl’s own lists of people appearing in the film with records from the Nazi death camp at Auschwitz in German-occupied Poland. She said her organization did not sue Riefenstahl for money.

“Leni Riefenstahl is a woman who cares for her own history she makes sure that only the truth she wants to read and only her version is published,” Pinkepank said. “But there are some survivors still living and we have contact with them and they want their version to be told, they wanted to have a voice.”

Frankfurt prosecutor’s spokesman Job Tilman said his office started a preliminary investigation, which could lead to criminal charges.

It is estimated that the Nazis killed at least 250,000 Gypsies during the Holocaust, in addition to 6 million Jews and people from other groups deemed racially inferior.

Although postwar American and French panels cleared Riefenstahl of responsibility for Nazi war crimes, she has been dogged by allegations she was more deeply involved in the Nazi cause than she admits.

Biographer Juergen Trimborn, whose “Riefenstahl: A German Career” was released this month, said Riefenstahl’s use of Gypsies showed she was willing to work within the Nazi system to advance her career.

“These people, she was only interested in them for her film and then nothing after that,” Trimborn said. “That they went on to die in the Nazi gas chambers of Auschwitz, she had no interest.”

German media reports on Riefenstahl’s birthday celebrated privately with nearly 200 friends near her Munich-area home reflect the difficulty many have in trying to reconcile her place in history.

“Old woman, or Hitler’s witch? Filmmaker of the century or the Fuehrer’s career woman? Pinup girl of the Nazis, or only narcissist?” wrote the top-selling Bild national newspaper.

In Die Welt newspaper, several of Riefenstahl’s peers, including “Basic Instinct” director Paul Verhoeven, focused on her contribution to filmmaking.

Verhoeven said Riefenstahl’s “Triumph of the Will,” a documentary of the 1934 Nazi party rallies in Nuremberg, was the work of a brilliant artist.

Jodie Foster, who is directing and starring in a film on Riefenstahl, said she hopes to depict both sides of the argument.

“She was perhaps one of the most important filmmakers of all time, and despite that, her work will remain bound with the horrors of National Socialist Germany forever,” Foster told Die Welt.