That person could be a benign and detached presence — just someone nonthreatening who can slowly defuse the ticking bomb. In my professional opinion, the dynamics of such interactions are very similar to what is done with those who paranoid and rageful individuals who take strangers hostage.
Is there evidence that the shooting was the product of a psychotic mindset?
Actually, the available evidence reflects substantial premeditation and planning to maximize casualties. The medical literature reflects that the more deaths in a mass shooting, the less likely an assailant was psychotic at the time of the crime. The more organized the behavior (in this case, chaining the entries to classroom buildings shut and controlling an entire building, quietly progressing from room to room, armed with changes of clips, Kevlar vest), the less likely a person was acting at the time with psychotic thinking.
In my professional experience, as exemplified in the Richard Baumhammers mass shooting, a person can have a major mental illness (in his case delusional disorder) and still not be psychotic at the time of the attack.
How is it possible for a person to have a psychotic condition, but not to be psychotic at the time of the crime?
For some — those who respond to a hallucination or who shoot only folks they have delusions about — psychosis is an element of the offense. Paranoid schizophrenia and paranoid delusional disorder are commonly implicated in mass shootings.
However, especially with schizophrenia, hostility is also a major component of the condition and the person with teeming hostility and rage is commonly quite alienated and emotionally alone. If that alienation advances into a resentment of a community in general, or a specific ethnicity or nationality, a person who carries out a mass shooting may be principally discharging rage — not acting under the influence of his psychosis. Baumhammers, for example, had a number of paranoid delusional ideas. He also, however, was politically anti-immigrant, resentful of minorities, deeply identified with family roots (from Nazi Latvia) and had a childhood history of burning a cross on a black family's lawn. He is an example of someone who had a psychotic condition, but when he carried out his condition acted on the objects of his rage, not the aspects of his psychosis.
This story has been updated to clarify the condition suffered by Richard Baumhammers.
Dr. Welner is chairman of the Forensic Panel, a national forensic science practice. An associate professor of psychiatry at New York University School of Medicine, he is developing an evidence-based test called the Depravity Scale, http://depravityscale.org, which invites Americans to participate in surveys that are used to form a legal standard of what represents the worst of crimes.