In 1964 James Chaney, Andy Goodman and Michael Schwerner traveled to Mississippi to help African-Americans register to vote, but in the process were murdered.
The United States Justice Department filed charges against eighteen defendants for violating the civil rights of the three victims. On October 20, 1967, seven men were found guilty. You can read the trial transcript at http://goo.gl/j73MQq. Also, there’s an excellent documentary called Neshoba: The Price of Freedom. The film focuses on Edgar Ray Killlen’s trial. He purportedly organized the murders.