Audit your processes
It never hurts to get an expert’s opinion on your internal policies and security procedures. He or she will not only help you audit your processes, but assist with violence-prevention training.  

Publish good policies
All employers should have an anti-violence policy. When was the last time yours was updated? Here are some questions to consider as you review your policy:

Is the policy clear—meaning, can someone who reads at the eighth-grade level understand it?

Does it cover threatening and bullying behavior?

Is it clear that the policy applies to everyone, including senior management?

Make sure everyone is aware of the policies
Your anti-violence policy may be in the employee handbook, but you should post it on the company intranet, in lounges, in the cafeteria and in reception areas.

Enforce policies
Never look away when you witness or receive reports about workplace violence. Tolerating or ignoring it suggests to those who violate the policies that you do not take them seriously.

Train managers
There’s no need to overstate this one: Companies have a responsibility to train their managers in violence prevention.  

Use safe interviewing processes
Put protocols in place for managers or HR representatives who conduct performance reviews or exit interviews with potentially dangerous employees. As an example, require that there be two people present, that the door be left open, and that any objects that can be thrown or used as a weapon be removed from the area.

Don’t ignore odd behavior
Discuss the behavior with the employee and see how he or she reacts. If appropriate, suggest that the employee take advantage of the company’s employee assistance program. If the employee agrees, wait to see what happens. If s/he disagrees, it may be reasonable to consider such refusal as a deeper issue.

If the behavior reaches a point where the workplace is affected and the employer believes it can be proved that the employee may be a “direct threat,” consider referring him for a fitness-for-duty exam with a psychiatrist. Be sure to consult legal counsel before doing this.