I believe what the guy's trying to get at is not that there haven't been serial killers before, but that there hasn't been one so skilled at hiding his/her intentions, and that's what makes it unique.
Has the killer avoided killing Blacks because he/she doesn't want to appear racist? Has the killer killed only one Black to hide the fact that it is racially motivated? Does the killer have inside knowledge of how law enforcement operates, and knows how to stay ten steps ahead? We've heard a lot of speculation about an ex-military type (not so much the skill required, as the discipline and stealth required), but I haven't heard much speculation about an ex-FBI, ex-CIA, or other LE type.