Video: 'The True Story Of Mississippi Burning | FULL EPISODE | The FBI Files'

(Sunday, June 21, 1964, victims released from jail and drove off in the direction of Meridian in a blue station wagon at approximately 10:30 p.m. CDT; during the Civil rights movement) — Three civil rights activists — Michael Schwerner, 24, and Andrew Goodman, 20, both Jewish New Yorkers, and James Chaney, 21, a Black local resident — were murdered tonight near Philadelphia, Mississippi, after being released from the Neshoba County jail.

All three were associated with the Council of Federated Organizations (COFO) and its member organization, the Congress of Racial Equality (CORE). They had been working with the Freedom Summer campaign by attempting to register African Americans in Mississippi to vote.

Since 1890 and through the turn of the century, Southern states had systematically disenfranchised most black voters by discrimination in voter registration and voting.

The trio had left Meridian at 9:00 a.m. to travel 40 miles north to Longdale to investigate the burning of a church.

After investigating the burning of the Mount Zion Methodist Church in Neshoba County, the three passed through Philadelphia and were arrested by Deputy Sheriff Cecil Price and taken to jail for allegedly speeding.

Video: 'From the Archives: "The Search in Mississippi"' (aired on the evening of Thursday, June 25, 1964)

They were released at 10:30 p.m. tonight and allowed to drive their blue station wagon back toward Meridian under a police escort.

The three were then abducted by members of the Ku Klux Klan, driven to another location, and shot at close range. The bodies were buried in an earthen dam on a local farm.

The civil-rights workers’ burnt-out car was found parked near a swamp three days after their disappearance.

An extensive search of the area was conducted by the Federal Bureau of Investigation (FBI), local and state authorities, and 400 U.S. Navy sailors. Their bodies were not discovered until seven weeks later, on Aug. 4, 1964, when the team received a tip.

In 1967, after the state government refused to prosecute, the United States federal government charged 18 individuals with civil rights violations.

Video: '1964 NBC NEWS SPECIAL REPORT: Chaney, Goodman & Schwerner!!' (aired Saturday, June 27, 1964, at 7:30 p.m. EDT)

Seven — Cecil Price, Klan Imperial Wizard Samuel Bowers, Alton Wayne Roberts, Jimmy Snowden, Billy Wayne Posey, Horace Barnette, and Jimmy Arledge — were convicted and another pleaded guilty, and received relatively minor sentences (3-10 years) for their actions.

After exhausting their appeals, the seven began serving their sentences in March 1970. None served more than six years.

Sheriff Rainey was among those acquitted. Two of the defendants, E.G. Barnett, a candidate for sheriff, and Edgar Ray Killen, a local minister, had been strongly implicated in the murders by witnesses, but the jury came to a deadlock on their charges and the Federal prosecutor decided not to retry them.

Forty-one years after the murders took place, Killen was charged by the state of Mississippi for his part in the crimes.

In 2005, he was convicted of three counts of manslaughter and was given a 60-year sentence (He would die in prison in January 2018).

On June 20, 2016, federal and state authorities officially closed the case, ending the possibility of further prosecution.