No-one has ever been convicted for the killing of the three activists
Klansman Ray Killen is charged with the notorious murders of three civil rights workers in the American state of Mississippi in 1964.
The case against him has re-opened the history file on the circumstances of the killings and the tense period of the fight for civil rights that summer.
The killings of black Mississippian James Chaney and white New Yorkers Michael Schwerner and Andrew Goodman have remained etched in America's collective consciousness and formed the basis of the film Mississippi Burning made in 1998.
The three were participating in Freedom Summer 1964 - an effort by hundreds of colleges students from the North to help to educate and register blacks to vote in the South.
On Sunday 21 June 1964, the three were driving to Meridian, Mississippi, when they were allegedly stopped by Ku Klux Klansmen on an isolated road outside Philadelphia.
James Chaney, 21, a black Mississippian from Meridian
Michael Schwerner, 24, a white New Yorker
Andrew Goodman, 20, a white New Yorker
They were arrested and held in the local jail, accused of speeding while driving to investigate the ruins of a black church that had been firebombed.
They were then released and later ambushed.
Chaney, 21, was beaten to death, while Schwerner, 24, and Goodman, 20, were shot in the chest.
Their bodies were found several weeks later, buried in an earthen dam on a nearby farm, after one of the largest searches ever undertaken by the FBI.
The station wagon they were driving had been burned.
Summer of rights
Freedom Summer 1964 was an education and voter-registration movement organised by civil rights groups in an atmosphere of overt racial hatred.
About 1,000 people, many of them college students, went down to Mississippi and other southern states to register black voters and fight segregation.
That summer saw some 35 black churches burned or bombed, 1,000 organisers and volunteers arrested and many more beaten.
Rita Schwerner Bender - the then wife of Michael Schwerner - recalls the climate of terror in which she and her husband worked.
"These murders, other murders and church burnings didn't happen in a vacuum," she told Mississippi's Clarion Ledger newspaper in an interview five years ago.
"There was an atmosphere of frenzy created. I believe strongly that history has to be understood because if it isn't understood, it gets repeated."
It was the 1963 Birmingham church bombing that killed four girls that inspired her and her husband to travel south and become part of the civil rights movement.
Many Mississippians were not happy to see outsiders telling them how to change and Ms Schwerner Bender said she often felt their hateful stares.
Howard Ball, the author of Murder in Mississippi: United States v Price and the Struggle for Civil Rights and a professor of political science at the University of Vermont, says Mr Schwerner was particularly targeted because he was a paid worker for the Congress of Racial Equality.
"The other two were killed simply because they were with Schwerner," he told the Associated Press news agency.
Many hope this and the other circumstances of the murders will be clarified in the new court case against Ray Killen.