Updated

Nearly 50 years after 14-year-old Emmett Till's (search) murder shocked a nation and galvanized the civil rights movement, his body will be exhumed as federal authorities attempt to determine who killed him, the FBI said Wednesday.

Till's body, buried in a cemetery in the Chicago suburb of Alsip, will be exhumed within the next few weeks so the Cook County Medical Examiner's (search) office can conduct an autopsy, said Deborah Madden, spokeswoman for the FBI's office in Jackson, Miss.

The black youth, who was raised in Chicago, was abducted from his uncle's home in the tiny Mississippi Delta community of Money on Aug. 28, 1955, reportedly for whistling at a white woman at a grocery store. His mutilated body was found in a river three days later.

The U.S. Justice Department announced plans last year to reopen the Till investigation, saying it was triggered by several pieces of information including a documentary by New York filmmaker Keith Beauchamp (search).

"The exhumation is a logical continuation of that," Madden said. "An autopsy was never performed on the body and the cause of death was never determined."

Two white men charged with the murder -- store owner Roy Bryant, the husband of the woman Till purportedly whistled at, and J.W. Milam, Bryant's half brother -- were acquitted by an all-white jury. The two, now deceased, confessed to the killing months later in Look magazine.

Beauchamp claimed to have uncovered new evidence in his documentary "The Untold Story of Emmett Louis Till."

R. Alexander Acosta, the assistant attorney general for civil rights, has said the documentary films and new information indicates the two had accomplices who may still be alive.

Though the five-year statute of limitations in effect in 1955 means no federal charges could be brought, Mississippi state charges could still apply, Acosta said.

The Till case gave many Americans a closer look at the segregated South, its Jim Crow laws and lynchings. The boy was killed a little over a year after the Supreme Court's landmark Brown v. Board of Education decision outlawed state-sponsored school segregation and about 100 days before Rosa Parks refused to give up her seat in the white section of a segregated bus in Montgomery, Ala.

Till's mother, Mamie Till Mobley, insisted that her son's body be displayed in an open casket at his funeral, forcing the nation to see the brutality directed at blacks in the South at the time. Mobley died in 2003. She is buried next to her son.