On August 4, 1964, the bodies of three civil rights workers—James Chaney, Andrew Goodman, and Michael Schwerner—were discovered in an earthen dam near Philadelphia, Mississippi. The three men had been missing since June 21, 1964, when they were arrested by local police in Neshoba County, then released and subsequently ambushed and murdered by members of the Ku Klux Klan.

Their disappearance was part of a larger campaign of violence and intimidation against civil rights activists during Freedom Summer, a movement aimed at registering African American voters in Mississippi. The FBI launched an investigation, codenamed “Mississippi Burning,” which led to the arrest of several Klansmen. However, state authorities initially refused to prosecute for murder, and it wasn’t until 1967 that seven individuals were convicted on federal conspiracy charges—none serving more than six years in prison.

The murders of Chaney, Goodman, and Schwerner became a turning point in the civil rights movement, galvanizing national outrage and helping to build momentum for the passage of the Civil Rights Act of 1964 and the Voting Rights Act of 1965.