I dont think Fred Phelps was a killer,he was an asshole , he was a civil rights lawyer , ran for state rep 3 times (D) lost.
I saw a graph from the Tuskegee inst (circa 2015) and they estimated that the KKK has killed aprox 20k ppl from the loss of the civil war to date. Blacks being the largest group of victims followed by Jews,Republicans,Hispanics and Italians.