The true crime documentary is a magnetic affair for many of us, particularly when murder is involved. We, the upstanding public, are utterly fascinated by people who kill—those unspeakable monsters we shun, yet devote hours of our free time indulging in their heinous work. What each of us finds so enrapturing about the horrific things one human does to another may vary from person to person, but perhaps the thing we all have in common as viewers—not participants—of these things, is that we recognize them as other. It’s not us doing the killing, not us being …