Thomas van Riper was an agent for the Federal Bureau of Investigation and sheriff of Anderson County, Tenn. He worked with informant Delmar Dennis to obtain information on murders perpetrated by Ku Klux Klan members in Mississippi, which lead to the convictions of Klan leader Sam Bowers in 1967 and of Byron De La Beckwith in 1994 for the 1963 murder of civil rights leader Medgar Evans. Van Riper died on August 11, 1997.

Former Confederate General Nathan Bedford Forrest, first Grand Dragon, established the Ku Klux Klan in Pulaski, Tennessee, in 1866. As members moved toward more violent and deadly actions, Forrest ordered the group to disband in 1869, though no one listened. After achieving its goal of white supremacy in the South, the KKK practically disappeared during the presidency of Ulysses S. Grant. In 1915 William J. Simmons reformed the Klan. It rose to 4 million members by 1925. However, as government officials became exposed as corrupt Klansmen, membership declined and the Klan was again disbanded in 1944. The emergence of the Civil Rights Movement in the 1950s and 1960s revived Ku Klux Klan organizations, including the most important called the White Knights of the Ku Klux Klan led by Robert Shelton.

In the summer of 1964, the Student Non-Violent Coordinating Committee organized a project in Mississippi to register voters, to build adequate schools for black students, and to establish community centers for medical and legal services. On June 20, 1964, Andrew Goodman, James Chaney, and Michael Schwerner traveled to Philadelphia, Miss.They were last seen in Neshoba County after being arrested for a traffic violation, and on August 4th their bodies were found shot, beaten, and buried on a farm. In December 1964, deputy sheriff Lawrence Rainey and 18 others were arrested in state court on charges of conspiracy, which were dropped. FBI Agent Tom van Riper had been working with Ku Klux Klan member and preacher Delmar Dennis to infiltrate Klan meetings and to inform the FBI on illegal acts perpetrated by the Klan. Dennis provided information to later convict seven of the men, including Klan leader Sam Bowers, in the 1967 federal trial for the violation of civil rights laws. Federal courts tried Preacher Edgar Ray Killen on conspiracy charges, but the jury was hung. Killen was again arrested in January 2005 and charged with three counts of murder.