BATESVILLE, MISS., JAN. 18 -- If ever a courtroom will serve as a time machine, it is now, as Mississippi travels back to a hot summer night in June 1963, when an assassin put a bullet into the back of civil rights leader Medgar Evers, killing a man but invigorating a movement.

Byron De La Beckwith, 73, an unrepentant white supremacist with the airs of a Southern gentleman, is being retried for the murder of Evers, who at his death at age 37 was field secretary of the National Association for the Advancement of Colored People in Mississippi, a job that required not only courage, but a fast Oldsmo bile, which Evers often used to escape from hostile towns.

Twice freed after all-white, all-male Mississippi juries failed to reach a verdict in 1964, Beckwith is accused of hiding in a honeysuckle bush outside Evers's house in Jackson and firing a single shot from his 1917 Enfield 30.06 rifle and killing Evers, who that day had called his wife three times to tell her he loved her.

Beckwith himself has publicly stated over and again that he did not murder Evers. His defense attorneys produced witnesses who say Beckwith was in Greenwood, some 90 miles from Jack son, near the time of the killing. Beckwith jokes that he is a good shot, but not that good.

But a young white prosecutor named Bobby DeLaughter, who has told reporters he never heard of the Evers case until after he graduated from Ole Miss law school, says he has new evidence -- and new witnesses -- who will put Beckwith in Jackson at the time of the murder and will testify that Beckwith bragged of killing Evers.

The trial, which began here today with jury selection, will be a journey back to a time and place that was as dark and violent as any in U.S. history, when white Mississippians used the power of government to enforce a brutal system of segregation that kept blacks out of schools, businesses and the voting booth.

"What a time warp," said Taylor Branch, the Pulitzer-Prize-winning author of "Parting the Waters," which traces the civil rights movement from 1954 to 1963.

The remarkable retrial and retelling of Mississippi history is made possible not only by DeLaughter's new witnesses, but by the emergence of evidence that the State of Mississippi itself screened potential jurors in 1964, possibly skewing the case in Beckwith's favor.

While many in Mississippi would like to see an old and great crime redressed, legal authorities here worry that Beckwith may be having his own civil rights of due process and a speedy trial violated.

Whatever happens, one difference is already apparent. At the opening today, Beckwith faced the first of the pools from which jurors will be selected over the next week. Among the 24 registered voters sitting in the dockets in 1994, any of whom could end up sitting in judgment of Beckwith, were 15 blacks.

Though many Americans would fail to recognize the name of Medgar Evers, most of the principal actors in the drama are still alive. Not only the man who stands accused of the crime, who sat today in the Panola County courthouse, cupping his hand to listen as potential jurors talked of their own lives and biases, but Evers's widow, Myrlie, and the men and women who worked for -- and against -- civil rights here in the early 1960s.

"Mississippi in 1963 was a police state," said Robert Moses, a former leader of the Student Nonviolent Coordinating Committee (SNCC) who now leads a project to teach algebra to African Americans.

"It was a state where its elected officials are promoting racism and all the terror that goes along with it," Moses said. "And Medgar is working right in the middle of this, surrounded by the violence used by the state to keep people in line."

John Salter, who was a sociology teacher at black Tougaloo College in Jackson and who started the NAACP Youth Council "with nine scared students" in 1961, recalls: "You could cut the fear with a damn knife. ... These were the most frightened people in the world."

Through this fear moved Medgar Evers and Byron De La Beckwith, in circles that overlapped and, if prosecutors are right, eventually fatally collided on the night of June 12, 1963.

Evers had served in the U.S. Army, and "he had something of a military bearing," said historian Branch. "He had served in the Army, and he believed he was entitled to certain rights, and that fueled his indignation."

After coming home to Mississippi, Evers graduated from black Alcorn Agricultural and Community College and started work as an insurance agent. He dreamed of becoming a lawyer, but he was refused entry into the University of Mississippi's law school, a school he would help James Meredith integrate in the fall of 1962.

In 1954 Evers took the NAACP job with the assignment of registering voters in a state where few blacks dared approach the courthouse. It was, said Moses, a state in which a man could be pistol-whipped for such civic-mindedness, as happened to John Hardy in Liberty in 1961. Hardy was arrested for disturbing the peace.

"Medgar was a model young man, a model for yesterday, today and tomorrow," said C.C. Bryant, who headed a local NAACP chapter.

"It's hard to describe what that time was like," said Salter, now a professor of Indian studies at the University of North Dakota and author of "Jackson, Mississippi." He recalls arriving with his new wife in 1961, driving across the old narrow bridge from Louisiana into Vicksburg in the middle of a summer night.

"And suddenly a group of men, heavily armed, with wide-brimmed hats, wearing bib overalls, stepped into the roadway and asked us where we're going," Salter said. They were the "border patrol." Salter told them, "We're just passing through."

What he discovered, said Salter, a part-Indian from Arizona who played a central role in the lunch counter sit-ins organized by Evers, was "a total segregation complex."

He tells the story of picking up an elderly black hitchhiker: "He just kept his eyes down, almost incomprehensible, telling me, 'Yes, sir, the best friend the old Negro man has is a Southern white gentleman.' Over and over. I finally had to stop him and say, 'Sir, you have me confused. I do not share those views.' "

Then Salter's passenger replied, in a clear voice, "Well, you know how it is."

Evers wanted to change all that. Byron De La Beckwith did not.

In 1963, the 42-year-old Beckwith was selling fertilizer and living in his family's slowly fading old home in Greenwood. Born in California but raised with deep roots in the South, Beckwith is said to have considered himself an heir of the Confederate aristocracy.

A World War II veteran like Evers, Beckwith served in the Marines and was decorated for his courage in battle on the Pacific island of Tarawa. He was also an expert marksman.

But Beckwith was also an avowed white supremacist who passed out pamphlets warning of the dangers of racial mixing. "I do believe in segregation like I believe in God," Beckwith wrote to the Jackson Daily News in 1957. "I shall make every effort to rid the U.S. of integrationists."

In the spring of 1963, the mass demonstrations of Birmingham, led by the Rev. Martin Luther King Jr., had captured the attention of the world, with pictures of Police Chief Theophilus Eugene "Bull" Connor unleashing dogs and water cannons on young marchers.

In Jackson, those close to Medgar Evers describe a man being pulled apart. The leadership of the NAACP was reluctant to use tactics such as mass actions with schoolchildren. They preferred lawsuits, boycotts and voter registration drives.

"Medgar was caught in a very tough position," recalls Salter, who had been cut, jeered and assaulted at a famous sit-in at a Woolworth's in Jackson in May 1963. That event led to wildcat mass marches and the arrests of hundreds of young blacks, a flourishing of protest that came to be known as the Jackson Movement.

The Rev. Edwin King, who was then a white chaplain at Tougaloo College, was at the Woolworth's sit-in where Slater and others were besieged by a white mob. With a pocketful of nickels, King called Evers, who orchestrated the protest, every 10 minutes, narrating the chaos.

"That was very much Medgar's sit-in and he never gets credit for it," King said. "I think he went through more anguish than anyone."

But the mass arrests and violence deeply disturbed the NAACP leadership, while it made Evers a target for white vehemence. "I believe there was a Molotov cocktail thrown at Medgar's house that night," King says.

After the mass demonstrations and mass arrests of early June 1963, however, the Jackson Movement began to slow, and then stumble.

"The movement in Jackson was sinking further and further down," Salter said, the anger of a few days in June spent.

Salter and King attended a small meeting with Evers on the night on June 11, 1963, at the New Jerusalem Baptist Church in Jackson. Evers did not give a fiery address. Instead, he tried to sell a handful of NAACP T-shirts that read: "Jim Crow Must Go." Salter remembers Evers seemed to him exhausted and quiet.

When he returned home after midnight, Myrlie Evers, who had slept after hearing President Kennedy address the nation on the need for civil rights, heard her husband's car. Then a single shot. She and her children hit the floor.

In the bushes was a rifle owned by Beckwith, with his fingerprint on the rifle's scope. Beckwith says his rifle was stolen. A jury of his fellow Mississippians will decide if he is telling the truth.