Offender and offense characteristics of a nonrandom sample of adolescent mass murderers

The authors conducted a descriptive, archival study of adolescent (< or =19 years of age) mass murderers-subjects who intentionally killed three or more victims in one event-to identify demographic, clinical, and forensic characteristics.

A nonrandom sample of convenience of adolescent mass murderers was utilized.

Thirty-four subjects, acting alone or in pairs, committed 27 mass murders between 1958 and 1999. The sample consisted of males with a median age of 17. A majority were described as "loners" and abused alcohol or drugs; almost half were bullied by others, preoccupied with violent fantasy, and violent by history. Although 23% had a documented psychiatric history, only 6% were judged to have been psychotic at the time of the mass murder. Depressive symptoms and historical antisocial behaviors were predominant. There was a precipitating event in most cases--usually a perceived failure in love or school--and most subjects made threatening statements regarding the mass murder to third parties. The majority of the sample clustered into three types: the family annihilator, the classroom avenger, and the criminal opportunist.

The adolescent mass murderer is often predatorily rather than affectively violent and typically does not show any sudden or highly emotional warning signs. Although the act of mass murder is virtually impossible to predict because of its extremely low frequency, certain clinical and forensic findings can alert the clinician to the need for further, intensified primary care, including family, school, community, law enforcement, and mental health intervention.