I am not sure if I may comment on this .. if not, mods, edit away!
Since JW's father commented during an interview that she is a "spoiled brat", gets her way, siblings don't like it, etc., I suspect JW's demeanor was the same even outside the home and therefore, some of those with whom she hung around with may hold the same opinion. Older kids 'tolerating' a six year old hanging around, etc. Of course, when it would come down to it, no one *really* disliked JW, we can be sure they probably cared for her and, I know for a fact per SM that some referred to JW as being their "little sister" in a sense.
Now, is it possible that GG found it 'easy' to do what he did to JW, based on the typical teen banter he would hear now and then (and perhaps knew that JW's father thought she was a "spoled brat"), that JW was a 'pain' or 'she's always' bothering us' or some such verbiage, and his self-justification was that he was doing everyone a favor and might come out of this a hero? Yes, a sick scenario of thought but I am attempting to determine how a seventeen year old described as being a 'shy, quiet kid' in social situations whom apparently has never given rise for anyone to suspect he could be capable of such a crime .. came about to actually commit such a crime.
Was it a purely sexual motivation, or are there other factors involved, such as the speculation above?