During the first week of September 1955, more than 50,000 mourners — mostly African-American and including young children — filed through Roberts Temple Church, in Chicago, past the open casket of 14-year-old murder victim Emmett "Bobo" Till. His un-restored corpse was a gruesome sight; on August 28, he had been kidnapped, pistol-whipped, shot in the head with a .45, then dumped in a river by two white men — 24-year-old Roy Bryant and his thuggish half-brother, 36-year-old J.W. Milam — in the minuscule Delta sharecropping town of Money, Mississippi. On September 23, the killers, who admitted to the kidnapping, were predictably acquitted of Till’s murder by an all-white Mississippi jury. Every attorney in the county participated in their defense.

The Till case has become a legendary example of American racist justice. It took place less than two years after Brown v. Board of Education made school integration a legal reality and three months before Rosa Parks sparked the Montgomery bus boycott. The American Experience film The Murder of Emmett Till — produced and directed by Stanley Nelson, with narration by Andre Braugher, and airing this Monday at 9 p.m. on Channel 2, does an excellent job of rehearsing the much-publicized facts of the murder, but more important, it places the incident in the pull-no-punches context of the nascent civil-rights movement and the institutionally racist South of the 1950s. (One of the film’s truly chilling sequences is an excerpt from a 1950s newsreel feature extolling — complete with chirpy public-service-announcement background music — "modern" segregationist practice in the South.)

According to witnesses, and to the killers, who shortly after their acquittal confessed to Look-magazine reporter William Bradford Huie (who published their account of the Till murder in Look’s January 1956 issue — see www.pbs.org/wgbh/amex/till/sfeature/sf_look.html), Emmett Till was targeted because he made "inappropriate contact" with Roy Bryant’s 21-year-old wife, Carolyn, who sold food and treats to black sharecroppers from the family store where the Bryants lived with their two children. Emmett Till was from Chicago, to which his mother, Mamie Till Mobley, had, when she was two, migrated with her family as part of the exodus from the repressive Jim Crow South. Reading between the lines of the recollections by his mother and his childhood friends included in Nelson’s film, you can see that Emmett was bright, a bit hyperactive, and definitely a smart aleck.

Exactly what the gregarious Till did to offend Carolyn Bryant is unclear. He was in Money visiting his uncle, a lifelong sharecropper named Moses "Preacher" Wright. And despite warnings from Mamie Till and the Wrights, young Till refused to take the race-separating conventions of Jim Crow Mississippi seriously. The Murder of Emmett Till recounts only what was witnessed: Till, upon leaving Bryant’s store, wolf-whistled at Carolyn Bryant. In the Look confession, Bryant and Milam elaborate, claiming that, goaded by other kids, Till touched the white woman, asked her for a date, and bragged to her that he had a white girlfriend in Chicago.

Either way, it was a fatal mistake. When Mamie Till (a teacher and activist who died in Chicago, at age 81, on January 6) decided to display her son’s mutilated body, which had been pulled from the Tallahatchie River and shipped to Chicago, his murder became international news. Sources in the film credit the subsequent publicity storm (Jet magazine ran photos of Till’s corpse) with fueling open opposition to Jim Crow in the ’50s and ’60s.

The PBS film is beautifully researched, showcasing still photos of the Till family, the whites of Money, and courtroom scenes. It also features a vintage interview with Moses Wright (who became the first black to testify against white defendants in a Mississippi court) and modern interviews with Mamie Till, Willie "Too Tight" Reed (who also testified against Bryant and Milam), other participants, and former Mississippi governor William Winter. The script draws sharp contrasts between the comparatively integrated North and the strictly segregated South of the 1950s. And it powerfully portrays the climate of fear surrounding early civil-rights activists and poor Southern blacks, as well as the monolithic draconian opposition they faced from poor-white racists.

This is not a routine documentary. It’s compelling and terrifying, as befits its subject, and viewers will have extreme reactions — to the faces of the smug white jurors and the killers’ complacent wives, and to the trepid courage of Mamie Till, Moses Wright, and Willie Reed. The Till murder alone did not create the American civil-rights movement, but it swayed a lot of sympathy to the desegregationist crusade and forever tarred the ’50s white rural South with a reputation for brutality and ignorance — which, this film will convince you, it fully deserved.

The American Experience has put up an impressive Emmett Till Web site at www.pbs.org/wgbh/amex/till/. Also, on Wednesday, January 22 at 9 p.m., Channel 2’s P.O.V. will air filmmakers Whitney Dow and Marco Williams’s Two Towns of Jasper, which explores the brutal 1998 race murder of James Byrd by three white Texans. Two Towns of Jasper will be accompanied by a Basic Black interview with Dow and Marco and then on Thursday, January 23, at 9 p.m., a live town-meeting forum on the case hosted, from Jasper, Texas, by Ted Koppel.