EXPERT: What Makes a Mass Killer?

Twice in 24 hours, a man brought a gun into a neutral situation -- a Salt Lake City shopping mall and a business meeting in Philadelphia -- and created a bloodbath. Besides the carnage, do these incidents share any similarities? What triggered this behavior? Do the gunmen have anything in common? And are there any behavior patterns that could identify these attackers before they strike? ABC asked ABC News consultant Dr. Michael Welner, a forensic psychiatrist and chairman of the Forensic Panel, to explain.

Cases such as the Philadelphia and Salt Lake City tragedies are often referred to as mass shootings. Why is that?

Because, from a forensic psychiatry standpoint, you have to consider that the mind-set of the person who carries out such an attack is the same, whether the attack kills or whether bullets merely fly.

The difference between a multiple homicide and a single homicide may be affected only, in these cases, by how accurate a shot someone is, or how fortunate a victim was that bullets did not mortally wound them.

I recall examining a mass shooter in Pittsburgh where the perpetrator killed three victims but shot two others in the head, who survived. To not group victims in such a spree together, simply when only one dies, is naive. Mass shooting covers the motive and speaks to the modus operandi and the leads that need to be understood by forensic scientists.

When we read about mass shootings, we hear that the people responsible are alienated loners. Is that all there is?

There are many alienated loners. Most don't kill. Nevertheless, mass shooters would not kill were they not to be so isolated, or so alienated. Depending on the setting, or the target, there are specific key ingredients to their personality, mood, life stage, triggers to the event, and sense of identity that combine, in the alienated loner, to a homicidal end.

How would a forensic psychiatrist differentiate between the Philadelphia mass shooting and the Salt Lake City mass shooting?

The Philadelphia mass shooting involved a workplace, financial interest setting; the Salt Lake City mass shooting involved a community shooting. In workplace settings, the killer feels emasculated by the target institution. He shoots to have the last word, by destroying the institution.

Not uncommonly, such shootings claim directors or presidents of target organizations, and victims who happen to be in close proximity to the killer. Even when a manager escapes, he may have been the primary target. Workplace mass shooters do not proceed beyond the boundaries of the office or chosen location to target random victims.

On the other hand, community shootings, such as the Salt Lake City case, do not involve a primary target or institution. The shooting may begin with someone the killer feels provoked him, or is symbolic of some perceived grudge. However, community mass shootings reflect someone with a substantial degree of paranoia and more general resentment toward the outside world. That paranoia may be a general suspiciousness and contempt of others or a full-blown delusional thinking.

Are there other important differences between workplace-investment mass shootings and community mass shootings?

The trigger in the workplace mass shooting is a clear and significant one. It is characteristically a loss of job or significant financial collapse in a person who had psychologically very much wrapped himself up in that workplace or company. More important, it is an event, or the shooter's perception of a loss of his identity.

This is why the workplace mass shooter is later found to have few other passions or diversions, and little prospect of returning to the workplace in a comparable capacity. That is also why so many of these killers, like the Philadelphia killer, are in the mid 30s-and-over age group.

Men who experience substantial financial or career collapse at that stage may recognize they are falling in a way that they will never again recover. They are bitter and do not want the people they blame for their failure -- never themselves -- to win. Killing those they blame, and killing the workplace guarantees this legacy. In the Philadelphia killer's case, he came to that meeting with a semiautomatic weapon -- this was not about events that arose during that meeting.

Community mass shootings are quite the opposite. The killer has a poorly integrated identity, whether he is adolescent or adult. An angry and destructive fantasy graduates into a righteous cause that gives a killer the notion of greatness through destruction.

By making a violent and dramatic statement about his grudge, or his grievance, or for others he claims to represent as similarly belittled, he is empowered. The attention and notoriety he knows he will get further validate his choice to become an antihero. In my professional experience, this is why community mass shooters are ready to die.

It is not just about being suicidal or even depressed. It is a sense that they are proud of an achievement, and reflects their view that they will never achieve a comparable level of greatness. Carrying out a mass shooting in a shopping mall that is a source of community pride aims to amplify media attention and community impact -- and personal notoriety as a result.

Is it surprising to read of a mass shooter who described by others as calm?

Mass shooters are frequently experienced by others as calm. This incongruous serenity speaks more to how dysfunctionally they express their anger than it does depict any particular condition or its severity.

Are there other important distinctions between workplace mass shootings and community mass shootings?

I can recall from my experience in the cases of Byron Uyesugi, the Hawaii Xerox mass shooter, and Matthew Beck, who carried out a mass shooting at the Connecticut lottery headquarters, another important distinction between workplace mass shooters and community based mass shooters.

The workplace killers demonstrate a meticulous degree of advance planning for the assault -- when it will start, how it will unfold, where they will target. Community mass shooters are more likely to reflect a modus operandi of starting and simply shooting at targets until they are killed. This distinction reflects in the workplace killers as more organized in their manner and thinking. Research has demonstrated that the more random the victims, the more likely the killer has a psychotic condition.

That said, community mass killers, if they target a specific ethnicity or preferred victim, may intentionally skip others who have nothing to do with the killer's perceived grievance. Paranoid thinking does not necessarily mean someone is not aware of what he is doing, even as the community may experience him as someone running amok.

Community mass shootings also differ in the actual event being out of proportion to the trigger that sets it off. The killer is someone who has nurtured a homicidal plan for some time, somewhat vaguely. The idea intensifies with despair. If there is a certain despair or sense or loss, which may have nothing to do with the killing itself, even a seemingly minor trigger will set the homicidal fantasy into motion.

That contrasts quite a bit from the workplace setting, in which a very clear stress and its impact on a person's workplace or financial identity will prompt the killer to wipe out the workplace literally and symbolically.

When you speak about a minor trigger, what are you referring to?

In my professional experience, the most common trigger is actually rejection by a woman the community mass killer had a romantic interest in. But other triggers have been identified and may instigate a fantasy into motion. The more psychotic the person is, the more likely the trigger relates to the psychosis.

What distinguishes multiple shooters from other killers?

All mass shooters are at the very least, ready to die. Some are suicidal, some are not. But in my professional experience, mass shooters do not prepare for life beyond their mass killing. Many mass shooters expect to be killed in the course of their assault and may even write notes they expect to have discovered after the crime. Some shoot themselves when they expect capture is imminent. Others make very clumsy efforts to escape an otherwise organized death scene ? not because they are disorganized, but for all of the meticulous planning they have done, for the attack, they have given comparatively little planning to getting away.

Is that lack of thinking far into the future the reason that we hear of adolescent shooters? Why is that?

To some degree. Because adolescents do not have the perception of time that adults do. Thirty years in prison, to a person who is 15 years old, is far more abstract an idea than it is to a 35-year-old. An adolescent who has not been incarcerated does not relate to court procedure and the criminal justice system the way a mature adult weighs the events to follow a homicidal attack. Homicidal impulses may therefore confront adolescents as well as adults. Adolescents do not have the same experience to steer them away from acting on those impulses, even though they recognize the enormity of mass homicide and the illegality of it. Adolescents also are more likely to be drawn into the allure of masculine identity through homicidal violence.

Is that why we don't see female mass killers?

Absolutely. There is nothing in our society that would elevate a woman's identity or her femininity through her ability to destroy. This truth reinforces my opinion of how important it is for us as a society to repudiate the connection between destruction and masculinity in order to develop the values we want our young people to carry with them even in times of emptiness and despair.

Dr. Michael Welner, a forensic psychiatrist, has examined several of this country's most well-known mass killers. He is chairman of the the Forensic Panel, (, a national forensic science practice of psychiatrists, pathologists and toxicologists. He is an associate professor of psychiatry at New York University School of Medicine and special consultant to ABC News. Welner is also developing an evidence-based test to assist criminal sentencing , the Depravity Scale, (, which invites Americans to participate in surveys that are used to form a legal standard of what represents the worst of crimes.