"Incident at Oglala" uses documentary techniques to make its case, but in the hands of Apted, an able director of both documentaries ("35 Up," "Bring On the Night") and narrative pictures ("Thunderheart," "Coal Miner's Daughter"), the film takes on a dramatic urgency that makes it as entertaining as it is informative.

This is a real-life murder mystery, and though it's apparent early on that Apted and Redford believe Peltier (who has been in prison since 1977) was railroaded by the system, they attempt to leave it open-ended so that the audience can make up its own mind. Unfortunately, that also makes some of the motivations and actual events a bit murky but in no way lessens the film's power.

Peltier was an American Indian Movement (AIM) activist, and the film contends that it was government zeal and prejudice against AIM, more than actual evidence, that forced a conviction. The evidence and legal maneuvering is complex, but Apted skillfully guides us through it, managing to make some larger statements about life on a reservation as well.

The contention that led to the killings, the film seems to say, is entangled with the long history of mistrust between American Indians and the U.S. government, rather than the specific events that led to this incident.

It's a strong argument that goes beyond the obvious. The filmmakers, by the way, have formally asked Congress to intervene and reopen the case.

"Incident at Oglala" is rated PG for violence and profanity.