Anthony DeFrances shot ArrowStream CEO, Steven LaVoie, before turning the gun on himself. DeFrances had been recently demoted, along with many other employees. (Thankfully LaVoie was not killed, although he's still in critical condition.)

As much as we'd like to believe that our companies are safe, that our co-workers are fine, and that no one we know's ex-partner will come to your office seeking revenge, it happens. I'm not advocating living in utter paranoia. Workplace murders are not common. You're far more likely to be killed in a car accident than in a workplace violence incident. Nevertheless, your company needs to be prepared, because it can happen.

Security expert, Gavin de Becker's book, The Gift of Fear, is a must read for everyone. Business owners should read it today if they haven't already. De Becker tells you what you should be looking for. The idea that no one could have foreseen, he says, is false. There are always signs, he says. Here are some of his thoughts from this book.

Trust your intuition.

Intution, de Becker says, is how we piece together clues that we can't quite yet articulate. When you feel suspicious, investigate, and don't look just for reassurance that everything is okay. Look for information that indicates that everything is not okay.

Don't be in denial.

When people say who could have known, they are justifying their own denial. I certainly don't blame them for doing so. Sometimes, though, denial runs deep. Forensic Psychologist Park Dietz, shared a story with de Becker about a man who murdered a co-worker, was convicted, sent to prison and then upon release, "was rehired by the same company whose employee he had murdered." He later killed another woman from this company.

The denial ran very deep in this company. When you have someone spouting threats or with a history of violence, don't think, "It can't happen here," because it can.

Offer support.

"The loss of a job can be as traumatic as the loss of a loved one," de Becker writes, "but few fired employees receive a lot of condolence or support."We don't make casseroles, send flowers, or raise money for friends when they lose jobs (although we should). It's not the cultural norm. When business owners and managers make the decision to terminate someone, they should do so with support Not just because it's the right thing to do, but because it can provide some protection.

I spent 3 years doing layoffs, and have been involved in the layoff of literally thousands of people. We always offered severance, outplacement, and extended health benefits and (importantly) employee assistance program benefits. We had an outplacement counselor meet with every single person directly after being notified of their termination--within 15 minutes. While this type of program can be somewhat expensive, remember your goal in laying someone off is to get them to go away quietly. Severance and access to someone who can help are the casseroles and flowers of terminations. Don't underestimate their psychological value.

Listen to your downline staff.

de Becker relates how when he asked a CEO of a large national company if his female restaurant employees had to deal with stalking, the CEO responded that it wasn't a big problem. When he asked the same question to the HR Director, he replied that they had had a few cases, but it wasn't a big problem. However, when he spoke to the head of the restaurant division, the answer was shockingly different. "We probably have two of those a month. I can think of about 20 we've had in recent years. It's a very serious problem."

In a start-up, you may only have 10 employees and you may know everything and everyone. But, as you grow, you want to make sure that serious matters, like stalking, are always brought to senior leadership's attention. Don't signal that you don't want to know about this stuff. You can't solve problems you don't know about.

Do your background checks.

Sometimes you're in a hurry and just want to get someone on board, so you skip the background check. This is common in lower level jobs. Don't. You are responsible for finding out just who you are hiring before you make the job offer.

Have good managers.

It's important to have managers that can get work done and can meet your financial goals, but it's also important to have managers that can manage people. de Becker says good supervision can be summed up in 6 words: "praise for performance--correction for errors." Don't just let things go and catch people doing a good job.

When you put off dealing with a problem employee, or have your entire staff walk on egg shells around a particular person, you increase your chances of a serious problem. Instead, deal with things directly and if you need outside help, get outside help.