I almost didn't watch "Valentine Road," the 2013 HBO documentary on the 2008 murder of Larry King in his classroom in Oxnard, CA. I have an aversion to the exploitation genre for which this story seemed tailor-made. Instead, the documentary draws you in with interviews of classmates, teachers, jury members, lawyers, Larry's friends and family, and friends of the murderer.
I'll leave it to you to form your own impressions, but I have to say that there are many ordinary people saying and doing unbelievably horrific things. My faith in humanity was definitely knocked down a notch after viewing.