The good news is that every case of workplace violence has been studied thoroughly. The vast majority of perpetrators have been with their organizations for years. Usually they felt that they had been denied a promotion they thought they were entitled to, or they had been terminated. In virtually every case, the perpetrators made threats beforehand.

Most people point to the post office as an example of a workplace that's prone to violence but the reality is, if you look at percentages, there's no higher percentage of threats and violence in most workplaces than there is in the post office. The difference is the number of people working there: there's actually more people employed at the post office than any other place in the U.S., except the military. So we have the perception that there's more violence but the reality is that the post office is just average.

Warning Signs of Violence
Here are the warning signs of violence. Most people who erupt into violence will exhibit more than one of these characteristic behaviors:

• Makes direct and indirect threats
• Mood swings, depression, bizarre statements, delusions of persecution
• History of Violence
• Domestic violence
• Verbal abuse
• Antisocial activities
• Physical or Romantic Obsession
• Substance Abuse
• Trouble with alcohol or drug addiction
• Depressive Behavior
• Self-destructive behavior
• Loner behavior or isolation
• Unkempt physical appearance, despair, sluggish decision-making
• Pathological Blamer
• Accepts no responsibility for his or her actions
• Constantly blames co-workers, employer, government, the system
• Impaired Ability to Function
• Poor impulse control
• Obsession with Weapons
• Ownership of gun or gun collection, combined with antisocial behavior
• Fascination with shooting skills or weapon-related activity
• Personality Disorder
• Antisocial or borderline personality disorders
• Irritable, aggressive, often involved in disputes or fights with others
• May steal or destroy property with little remorse
• Borderline personality shows moodiness, instability, impulsive action, easily agitated

Clearly, you have both the right and the responsibility to intervene if you see behavior that is threatening or violent, or that you, in good faith believe might lead to threats and violence. This is an area where being proactive is always a good idea. Don't wait until it's too late. While actual incidents of violence may be rare, when one happens, the consequences are so grave that you must take action ahead of the curve.

Preventing Violence
Experts agree that effective pre-employment background checks are crucial. Before hiring any applicant, check references and ask specifically if there is any history of violent or harassing behavior. Even if the references refuse to answer the question, you have taken reasonable steps to screen out potentially violent employees and that will help you if you're ever sued.