Third, the criminal psychology doesn't track. Frat guys can be lots of things. They can be drunks, they can be rapists, they can be great guys, and those things all at the same time. They can be great students and whatever to. But, they aren't born killers, this isn't a group like ex military, or a group of dudes just out of the pen. There is a certain level of vioence that comes from a group of men that is built on rituals, and male bonding, and competition, sure, but the idea that they killed 4 people in cold blood, is unlikely, to say the least. This is one killer. I've read dozens of books on these kinds of things, it's one killer.