Can shootings be averted by knowing what traits to look for?

The man never talks.

When co-workers greet him, he looks down and mumbles, "Hi."

When he's mad, he silently simmers, and other employees steer clear. He's very intelligent, a co-worker says, but "different."

Is he just an introvert? Or potentially explosive?

Sometimes it can be tough to tell the difference. Yet, in the aftermath of shootings like the one at Northern Illinois University, the search goes on for behaviors or personality traits that, if only they'd been noted, might have averted violence and tragedy.

Warning signs for violent behavior exist, but they're not necessarily the ones you'd expect. External signs, like the NIU shooter's violent tattoos, aren't the focus of most profiles of potential killers. A sudden change in demeanor can be a sign of trouble, such as abruptly going off antidepressant medication and suddenly deciding to get tattoos, as the shooter did.

Experts say it's difficult to recognize the warning signs, especially against a backdrop that seems relatively normal, like the NIU shooter's academic achievements, friendships and relationship with his girlfriend.

The FBI has a broad list of traits exhibited by school shooters. Almost everyone would have at least one of the traits, and a person with all of them surely would be recognized as a potential threat. Someone who falls in the middle of the spectrum can be hard to identify.

"There is no one-size-fits-all profile of a school shooter," said former FBI profiler Gregg McCrary. "People like (the NIU shooter) just fall off the radar screen, and no one picks up on it until it's too late."

It's possible for them to be so deeply paranoid and able to mask it so well that no one detects the depth of mental illness, he said.

"When that happens, no one has any idea that they're as disturbed as they are," McCrary added. "It becomes virtually impossible for anyone to see these people coming."

Suzanne Andriukaitis, director of the Greater Chicago National Alliance for Mental Illness, believes people who commit violent acts usually do give warning signs, but people around them don't take them seriously. Those signs can include social withdrawal, bizarre behavior or stopping medication without a doctor's consent.

The Virginia Tech shooter gave numerous potential warnings, including a violent essay and reclusive behavior, yet no one picked up on it.

"Often, family and friends will say, 'Oh, you didn't mean that,' and try to ignore it. What we tell people is, don't ignore that sort of thing and encourage that person to get some help. If they don't want to go on their own, you might have to help them go," she said.

People tend to interpret visible signs as warnings. Tattoos or all black clothing aren't on the FBI's list of potential warning signs. Fascination with violent music, movies and video games is noted on the FBI list, but by itself it applies to many nonviolent people, too.

Likewise, most mentally ill people aren't dangerous, although depression and narcissism are on the FBI list. In fact, people with mental illness are far more likely to be crime victims than perpetrators, according to the National Alliance for Mental Illness.

"Most (mentally ill people) are fearful, stay at home and reduce their level of stimulation from the outside world. When people are dangerous, there are usually substances involved. They get some chemical courage," Andriukaitis said.

Trying to identify warning signs for violent behavior is not only a challenge for family and friends, but for school counselors, police officers and human resources staffs.

The problem is, it's hard to predict whether someone who's acting erratically can be dangerous. Most of the time, they're not.

Des Plaines Police Chief Jim Prandini said the most outwardly troubled people his officers deal with are homeless, and yet they are not the ones who commit violent acts.

"There are people who you talk to for two minutes and you know they have issues. But I'm not sure they are the ones we need to worry about who are shooting up schools," Prandini said.

Police officers who encounter people acting delusional often will bring them to the hospital or call their families. But Prandini said these people often are back on the street the next day because of underfunded mental health programs and inattentive families.

"It's easy for law enforcement to see how people slip through the cracks like this. Then they'll move out of the area and there'll be no record on it," Prandini said. "If we'd have picked up (the NIU shooter), for example, we would have had no idea that he was discharged from the military for psychiatric reasons. There's no database of information."

Unusual and bizarre behavior in the workplace also leaves human resources staffs to struggle with the decision of whether someone's unusual behavior poses a threat.

"It's often difficult to evaluate the potential threat," said Ingrid Markwort, senior account manager at Schaumburg-based Workplace Solutions, a company that works with human resources departments. "You have to be careful. We don't want to get into the business of diagnosing danger."

She encourages anyone with an uneasy feeling to report it.

"It's better to have someone look into it than ignore it," she said.

Experts say the best way to evaluate whether someone is truly dangerous is to trust your gut instinct.

"No one just snaps. That's a myth," McCrary said. "There's usually a period ... where they're in this downward spiral. If you catch it, maybe you can stop it."

Warning signs

An FBI report, "The School Shooter: A Threat Assessment Perspective," includes a list of warning signs. More detailed descriptions are at www.fbi.gov/publications/ school/school2.pdf.

Personality traits, behavior

• Leaks clues to feelings, thoughts, fantasies, attitudes or intentions for a violent act

• Low tolerance for frustration

• Poor coping skills

• Lack of resiliency

• Failed love relationship

• Nurses resentment over real or perceived injustices

• Depression

• Narcissism

• Alienation

• Dehumanizes others

• Lack of empathy

• Exaggerated sense of entitlement

• Attitude of superiority

• Exaggerated or pathological need for attention

• Externalizes blame

• Masks low self-esteem

• Anger management problems

• Intolerance

• Inappropriate humor

• Seeks to manipulate others

• Lack of trust

• Closed social group

• Change of behavior

• Rigid and opinionated

• Unusual interest in sensational violence

• Fascination with violence-filled entertainment

• Negative role models, such as Satan or Hitler

• Increasingly occupied in activities that could be related to carrying out a threat

Family dynamics

• Turbulent parent-child relationship

• Acceptance of pathological behavior

• Access to weapons

• Lack of intimacy and closeness with family

• Parents set few or no limits on child's conduct, regularly gave in to his or her demands

• No limits or monitoring of TV and Internet

School dynamics

• Student detached from school

• School does little to prevent, punish disrespectful behavior

• School discipline is inequitably applied

• Inflexible culture

• Certain groups of students are officially or unofficially given more prestige and respect than others

• A "code of silence" prevails among students

• Access to computers is unsupervised and unmonitored

Social dynamics

• Has easy, unmonitored access to movies, TV, computers and video games with themes and images of extreme violence

• Intensely and exclusively involved with a group who shares a fascination with violence or extreme beliefs

• Drug and alcohol use

• Copycat effect