Saturday marks the 50th anniversary of the killing of three civil rights workers in Mississippi, a pivotal moment in the 1960s struggle for equality. On June 21, 1964, James Chaney, Andrew Goodman and Michael Schwerner were ambushed by a gang of Klansmen. The three were beaten and shot, their bodies found weeks later buried in an earthen dam. They had come to Mississippi to register African-American voters as part of the Freedom Summer campaign. A number of Klan members were convicted on minor charges, with none serving more than six years. It took 41 years before a murder conviction was handed down in the case, with former Ku Klux Klansman Edgar Ray Killen found guilty of manslaughter in 2005.