Her Hitler-commissioned masterpieces of the 1930s ""may be the two greatest documentaries ever made"" (Susan Sontag's blurb), but filmmaker, actress, and notorious woman Riefenstahl will probably be remembered for her personification of the artist-as-propagandist dilemma. Infield intends to make sure that she is remembered as, at best, an amoral opportunist. His apparent form is chronological biography, but the deep structure is courtroom cross-examination, with prosecutor Infield taking on Riefenstahl's after-the-fact defenses and demolishing them with letters, Nazi inter-office memos, interview transcripts, and the public record. Riefenstahl claims mere acquaintanceship with the Fuhrer? Infield shows her, for a start, disappearing for days, returning in Hitler's private plane, and telling all of having ""just passed through a wonderful experience."" Riefenstahl reminds us of her art-vs.-propaganda feud with Joseph Goebbels? Infield documents an indomitable Leni and an acquiescent Goebbels. Riefenstahl pleads ignorance of the mistreatment of Jews? Infield scoffs and reproduces public edicts. The Torquemada-like marshaling of evidence impresses and convinces, but zealous excesses--naive shock at Hitlerian hypocrisy, occasional jumped steps in logic, too many footnotes--mar the victory. Other drawbacks: a deficiency of cinema expertise and a postwar wrap-up that trades care for brevity. No mention, for instance, of Riefenstahl's recent photo-book, The Last of the Nuba, which Sontag has used in formulating a ""fascist art"" esthetic. So this is not the Riefenstahl book--far from it--but its indictment will stand until the real thing comes along.