The problem here is the word "planned." When normal people say that, we imagine a logical, coherent, reasonable mind setting a goal and then planning steps, imagining obstacles, and arriving at a "plan." The sort of people who do mass murder do not think the way we think. I've referenced Cullen's book on Columbine here before; he describes in detail the "plans" one of the killers made, intending to slaughter 500+ people by setting off bombs in the school. It's a lucky thing for many that the bombs were duds and he/they failed. It wasn't for lack of "planning." It's that these people are not like us. They are wired differently mentally and emotionally. Their "motives" and "plans" do not resemble what we call motives and plans. I mean, if someone STARTS with the thought, "I'm going to break into a house and kill all the college kids living there," what plan, exactly, is going to make sense when the objective is monstrous, malignant, and inhuman. We realize that what he intended to do was horrific and nothing we would ever consider but we miss that his other decision-making processes are similarly distorted. Not all of them get caught, but not all of them decide to slaughter 4 people in one house either, in the era of DNA, forensic genealogy and mass surveillance.
