KNOW YOUR MASS MURDERERS

Do you know your history? Wanna take a trivia challenge? In the comments, name the 4 individuals above and match them to the senseless mass murder scenes below for which they are responsible. Extra credit: Name the countries the individuals are from; the approximate dates of the crimes; the nation(s) against whom the crimes were committed; and how these criminals met justice. Pencils up... Good luck... You may begin.