By Liz Ryan
and Lara Nicholson
LSU Manship School
News Service
A retired FBI agent was at a Christian retreat in the late 1990s when a churchgoer confided that he had witnessed a shooting of five Black men in 1960 that he believed had been racially motivated.
And when Congress started to pressure the FBI in 2007 to investigate dozens of cases involving violence by the Ku Klux Klan and other…