Dr. Susan Lipkins

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Dr. Susan Lipkins, a psychologist and expert on hazing, analyzed some of Cho's writings. "I found that he had really lost his connection with reality," she says. "The amount of violence and the rambling are similar to people who are schizophrenic, who have some other kind of psychotic disorder, and that it was very, very clear that this man needed psychological intervention immediately."

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Based on Cho's writings, Dr. Lipkins says she is not surprised he became a shooter. "Violence is rarely random. It's planned, as it was in this case. It's the victims who are random," she says. "We have to teach people how to stand up and protect themselves."