"The Thin Blue Line" is a movie unlike any you have ever seen before.

This extraordinary documentary, directed by the very talented Errol Morris, is a matter-of-fact, no-apologies, detailed murder investigation, looking into the 1976 killing of a Dallas police officer who innocently pulled over a car one night because its headlights were off. The driver pulled a gun and shot the policeman five times.

Morris goes through the expected motions in his own investigation, using cinema-verite interviews with most of the principles involved, including police; lawyers on both sides; the judge who oversaw the case; Randall Adams, who was convicted of the crime and has spent the past 11 years in prison; and the man who fingered him, David Harris, himself on Death Row for another murder.

But Morris goes several steps further by using fictional moviemaking techniques to visualize what is being talked about, including movie clips to illustrate specific testimony, a mesmerizing Philip Glass score to add to the mood of tension, and dramatic recreations that show several different points of view as they are described by those interviewed.

Though the film wastes no time plunging into the step-by-step investigative process, Morris uses the first half of his movie to more or less set up the second half, which makes a very strong case for Randall Adams' innocence.

In fact, Morris' final interview with David Harris has him virtually admitting that he was actually the killer.

Unfortunately, just before meeting with Harris one last time, Morris' camera broke down and he had to use a cassette tape recorder to interview him. That may have worked to his advantage, since Harris might not have been so loose of tongue had a camera been on his face again. But it certainly doesn't stop Morris from using that interview in a powerful cinematic manner so that its impact on the audience isn't at all lessened.

In fact, the film has been the basis for the Texas legal system taking another look at the case. An update in the current issue of People magazine (Dec. 26-Jan. 2) says a judge recommended this month a new trial be granted Adams because the movie discredits much of the original testimony. That recommendation is now in the hands of a higher court.

See this movie and you will agree that a new trial is the least that Adams deserves.

You will also be moved — mostly to outrage at the obvious injustices perpetrated in the name of justice.

Morris' other films are hilarious comic documentaries — "Gates of Heaven," about people who bury their pets in special cemeteries, and "Vernon, Florida," about the eccentric residents of that small town — which hardly prepare the viewer for the powerhouse picture he has made in "The Thin Blue Line." But his first foray into drama may be the first documentary thriller. And an excellent debut in this genre it is.

"The Thin Blue Line" is not to be missed.

It is not rated, but would probably carry a PG-13 for recreated violence, a couple of profanities and a brief sex scene with some nudity, a clip from the R-rated film "Swinging Cheerleaders," which is pertinent to testimony.