"The pattern starts with a period of brooding, distress, preoccupations and depression," said Arboleda-Florez. "After a period, the guy grabs a weapon and starts a non-provoked outburst of attacks ... (he) just attacks and kills and maims and then commits suicide."

Many psychiatric experts were cautious about linking Cho's rampage to amok because it is described in the current American Psychiatric Association manual of mental disorders as a "culture-bound syndrome." Besides the problem of stereotyping that that raises, they argued that using the construct might suggest Cho was not suffering from a mental illness, when in fact he seemed deeply disturbed.

Francis Lu, a psychiatrist at San Francisco General Hospital, said the classification of amok needs to be reconsidered in the psychiatry manual, which is now being revised.

Lu, Saint Martin and Arboleda-Florez also emphasized that Cho's Korean ethnicity was a red herring in this context. The fact that experts once believed amok was limited to Asian cultures said more about the biases of those observers than the cultures they purportedly studied, Arboleda-Florez said.

While it is difficult to diagnose Cho after the fact, there were several signs he suffered from serious mental illness, Lu said. The videos Cho made suggest "he was grossly delusional with paranoia and psychotic," the psychiatrist said.

While cautious about the stereotyping implications, however, Lu said amok could describe a pattern of behavior among people who suffer from a range of different underlying mental disorders.

Gerald Koocher, a former president of the American Psychological Association, said Cho might have been suffering from a personality disorder that has some similarities to schizophrenia.

Harvard psychiatrist Richard Mollica said the tragedy underscored the extent to which depression in America goes untreated. In late 2005, Cho received a mental health exam that suggested he was depressed. He denied being suicidal.