The Gra talks about people who steal and kill and those who just steal. The root of the former is that the attitude that the person who owns the object I want is holding on to what really belongs to me and HE is in my way. In order to "right this wrong" he kills him and takes the object. In the latter case it is not about the PERSON who is in his way but rather is about the object itself which he feels belongs to him. So he takes it for himself and leaves the original owner alone.
On that and much more - here.
