have been reading a book on the Hungerford massacre in 1987.
the end has this bit
For contrary to popular opinion, there is little evidence of insanity among the majority of mass killers. In a forty-two-case sample study by the American criminologists Levin and Fox, only around one in five killers attempted to plead not guilty by reason of insanity. And of those who did, less than half would manage to convince a jury.
In their authoritative report Professors Levin and Fox went on to present a ‘composite profile’ of the multiple-victim killer. They came to the conclusion that the great majority of such killers were not insane; that, in layman’s terms, they were bad rather than mad: ‘He is typically a white male in his late twenties or thirties. In the case of simultaneous mass murder, he kills people he knows with a handgun or rifle; in serial crimes, he murders strangers by beating or strangulation. The specific motivation depends on the circumstances leading up to the crime, but it generally deals directly with either money, expediency, jealousy, or lust … Finally, though the mass killer often may appear cold and show no remorse, and even deny responsibility for his crime, serious mental illness or psychosis is rarely present.’
The two academics were also able to identify a number of factors which, they believe, are consistent with almost every case history of an indiscriminate killer. First of all, they argue, there has been a life filled with frustration. Secondly, there has been a precipitating event, such as unemployment or divorce. Then there is access to and training in the use of firearms. And finally there has been a breakdown of what is referred to as ‘social controls’, such as occurs when a person moves to a new town or an important relationship breaks up.
Link