death drip or shrink

Colorado shooting suspect James Holmes was seeing psychiatrist at university before massacre - The Washington Post

Vengeance may demand a blood sacrifice in atonement for the massacre in the theater but it seems obvious that one does not do things like this without some mental derangement.  Schizophrenia would fit the bill for the murderous behavior but may not be enough to satisfy the public.  However, it would allow for the planning and meticulous execution.