Humans who do evil deeds

Teacher Becki Norris writes about her former student in her article "Why I Testified on Behalf of Dzokhar Tsarnaev"

Why do we feel the need to believe that monstrous deeds can only be committed by those who are evil to the core? Is it too difficult to see the world in shades of gray, too disturbing to confront the idea of a good person turning to unspeakable acts? Over the past two years, I have had to accept that a kind and gentle temperament is not a lifetime guarantee, and a smart and caring child can go far, far down an evil path. I have discovered the painful truth that when you care deeply for someone, that does not stop even if he does unfathomably horrible things. We humans are surprisingly good at holding two irreconcilable ideas in our psyches at the same time. Yes, he did the unforgivable. And yes, I still love him. And — this one is hard to fathom, I know — he is a human being who still needs love.