Here's the problem: we psychologists have plenty to say about suicide, anti-social personality disorder, and psychosis, but we haven't developed accurate methods for predicting the kind of rare deviant behavior that occurred at VU. Sure, you can say socially isolated people are more likely to go off the deep end, but social isolation is not an accurate predictor of this behavior, because the vast majority of socially isolated people do not act this way. I know it would be reassuring if these kind of events could be accurately predicted, but people are way more complicated than that.
[WS:] I think it is only a problem when you limit yourself to paper-and-pencil testing. If, otoh, you start observing the suspect (identified based on those test) and see in what kind of behavior he engages in everyday life - is he being set off by trivial events, is he aggressive, does he torture animals, is he trying to acquire weapons ? then the predictive power of your profiling will increase rather dramatically. .
Wojtek