Unfortunately, when you have an unreasonable person who wants to kill someone and doesn't have something as compelling as their own safety to worry about (since they don't mind killing themself after the deed is done), preventing these kinds of incidents is not an exact science. Not even close. Here's some links on the topic:
- FBI Workplace Violence: Issues in Response
- Workplace Violence Articles
- OSHA Workplace Violence Prevention
- USDA Handbook on Workplace Violence
A couple of ideas for preventing this type of situation (from yours truly):
- Work for yourself (in a location/situation of your choosing)
- Don't have employees
- Make good personal choices (such as choosing significant others who aren't violent/crazy/have major personality disorders)
- Be ultra aware of your surroundings at all time
- Get in the habit of safety (locking doors behind you, etc)
- Always be prepared to defend your life if necessary
- Be consistently inconsistent
- If you are aware of a threat situation (ie: a relative involved in a domestic violence situation) take planning steps/action immediately
- Don't rely on the police/a protection order/a video camera to protect you. The only thing that will stop a homicidal maniac is firepower. Period.
The bottom line is that these situations are random and unpredictable, however there are usually plenty of warning signs ahead of time. Don't dismiss these warning signs.