It takes a really special (and by that I mean fucked up) individual to do something as horrific as that. One of the kindest, most caring people I've ever met is a Muslim gentleman and his family who lives next door to my elderly parents. He introduced himself shortly after they moved in. I'd often see him in his yard when I stopped by and we'd chat about all sorts of things.
One day he said, "here's our numbers. If there's ever an emergency or need me to check on your parents, please don't hesitate to call us. I know you're a busy person, don't live around the corner and you can't always be there on a moment's notice. In my religion we are taught to help our neighbours who live on either side of us." I had no problem giving him a key in case of an emergency. He's helped out my parents on numerous occasions.
Like I said, one of the nicest families I've ever met. It's just sickening, that individuals like that piece of garbage who killed that family live among us.