For 50 years, Emmett Till, whose lynching galvanized the civil rights movement, lay buried outside Chicago while his killers in Mississippi went unpunished.

Now federal investigators are about to intrude on the 14-year-old murder victim's eternal slumber - and possibly bring his family a measure of justice.

Within days, they will exhume Till's body from its resting place at the Burr Oaks Cemetery in Alsip, Ill., to perform an autopsy and examine his remains for clues to his killing.

And they''ll be doing it because a Brooklyn filmmaker refused to let Till's story fade away.

"It's been a 10-year journey to get the full story told," said Keith Beauchamp, whose documentary about Till triggered the renewed federal investigation. "It's surreal to me that this is finally happening."

Two white men - both long since dead - escaped punishment even after admitting to killing Till in August 1955 and dumping his body in the Tallahatchie River.

But Beauchamp uncovered new evidence in "The Untold Story of Emmett Louis Till" that could lead authorities to at least five accomplices who are still alive, the feds said.

Though the federal five-year statute of limitations on civil rights crimes has long since expired, any new suspects could still face Mississippi state charges.

Till was found wearing a barbed-wire necklace weighted down by a 70-pound electric fan, but an autopsy was never performed.

"I can''t answer that," said Joyce Chiles, the current district attorney in Greenville, Miss., when asked to explain why. "This is a natural and necessary part of any investigation."

Till, who grew up in the Windy City, was visiting relatives in the hamlet of Money, Miss., when he was mutilated and killed. Half-brothers Roy Bryant and J.W. Milam were charged in the bestial crime.

Witnesses at their trial insisted Till brought trouble on himself by wolf-whistling at a pretty young store clerk - Bryant's wife, Carolyn.

Bryant and Milam were acquitted by an all-white jury, sparking national outrage. They later boasted - in the pages of Look magazine - about killing Till.

"N-----s are gonna stay in their place," Milam said. "And when a n----r gets close to mentioning sex with a white woman, he's tired of living!"

Carolyn Bryant was suspected of helping her husband kidnap Till, but she was never charged with a crime. She later divorced Bryant and moved to Greenville. Now 70 and known as Carolyn Bryant Donham, she did not return a call for comment.

Till's murder disgusted the country and exposed the shocking situation of blacks in the segregated South.

His mother, Mamie Till Mobley, insisted that Till be displayed in an open coffin so the world could see how savagely he was beaten and pistol-whipped.

"I''m sorry she isn''t alive to see this happening," said Beauchamp, 33, who lives in Fort Greene. "This is something Mrs. Mobley discussed before her passing two years ago. She knew this was going to happen."

*The attached picture of a beaten Emmett Till is graphic, but that is what true racial hate can do. His casket remained open at his funeral, by his mothers request.