"Justifiable Homicide" examines the questionable police shooting of two young Puerto Rican men in the Bronx in early 1995, an incident which presaged the linking of New York City with police brutality in headlines across the country. Filmmakers Jonathan Stack ("The Farm") and Jon Osman never try to hike their partisan bias. But the real story of "Justifiable" is the amazing politicization of Margarita Rosario, the mother of one of the boys, in her journey from conservative Rudy Giuliani supporter to political activist and founder of "Parents Against Police Brutality." Film's release, originally skedded for September, was delayed for obvious reasons. In the interim, Rudy Guiliani has gained legendary status. Domestic future of doc, which casts Giuliani in a decidedly negative light, may hang on future metamorphoses of the mayor's historically volatile public image.

Before 9/11 turned Giuliani into a national hero, the mayor's popularity had been seriously undermined by his self-appointed role as fanatical apologist for New York's Finest -- even in the face of the sodomization of Abner Louima by police while in custody, and cops firing 41 bullets into an unarmed Amidou Diallo.

Film makes a strong case for some form of miscarriage of justice and subsequent high level cover-up in the Rosario shootings. It spends a lot of time with members of the independent Civilian Complaint Review Board that investigated the case and found the shootings and following police inquiry highly suspect.

But films that seek to convince through painstaking accumulation of detailed evidence seldom succeed in convincing the skeptical: If such pics show something vital had been left out of the evidence, the skeptical feel something equally vital may be left out of film they are watching. But here each revelation, precipitating a further stage in the emotional and political evolution of Rosario, gains resonance as a measure of her frustration.

If "Justifiable" posits the strong, articulate, beauteous Rosario as its heroine, following her as she reminisces while preparing a meal, comforts a grieving father or organizes another march, one doesn't have to look far for the villain -- one of the cops involved in the shooting was a volunteer bodyguard for Giuliani. Pic's high point, captured by a hidden camera, concerns an infamous session of the mayor's phone-in radio program where Giuliani, asked by Rosario why her son was repeatedly shot in the back while lying on the floor, lashes out at her, blaming her for her son's death. Lensing and tech credits are suitably gritty; Latin-toned music score by Wendy Blackstone gives pic a comfortable neighborhood feel.