Complex sentence: Medgar Evers lived with the constant threat of death upon him, with a heavy Ku Klux Klan and white supremacist population in the area in which he both lived and advocated.
Split into simpler sentences: Medgar Evers lived with the constant threat of death upon him. A large Ku Klux Klan and white supremacist population existed in the area in which he both lived and advocated.