I think we go off course by hurriedly making assumptions of motive, other than the obvious that this is a very troubled and evil young man. He was caught in Lake Forest, a few blocks from where my mother was raised, right across the street from the Bears headquarters. He is no expert criminal. I can't think of a worse place to hide if you are wanted than Lake Forest, Illinois. My family goes back four generations in Lake Forest. The first forebears were servants for the McCormick estate in Lake Forest.
The kid is from Highwood. It is in the Highland Park high school district, and it is largely a hard working Italian and Hispanic community with roots in supporting business connected with Fort Sheridan when it was operating. Highland Park is both liberal and very Jewish (indeed, the first place my wife and I lived after getting married - she is Jewish and felt very comfortable in Highland Park). Highland Park has wealth along the lake, lots of it. Highwood likely votes blue, but is a far different culture than Highland Park. My brother's first wife is from Highwood, and I know the people well. While in general I observed no problems there when I was growing up, and the kids were more fun than many of the academic drones, I could see where an erstwhile rapper with social interaction problems like this kid (his photos speak to being odd) could feel alienated in a high performance academic culture. But Highland Park is very tolerant as things go, so no excuse there. It is just too early to speculate on politics and motive.
His parents are toast - they are going to have to move and their life will not be pleasant. Small potatoes compared to the victims.