We always knew it!

Okay, why is it that every time some person goes off the deep end and commits some crazy act of violence the news interviews the person's neighbors who say, "We never expected this from him/her. He/she was always such a quiet person"?
Just for once I'd like to see the next door neighbor say when interviewed, "We knew from the first time he burned down the house that he would end up this way; we just weren't sure when," or I'd love to hear the person's first cousin once removed say, "He was a jerk, we always knew it, I expect nothing more than this," but you never see it.
Sure, we can't probe the deep topics all the time. . .