Rarely do thieves get away with stealing once, and then quit. If you ignore minor losses, you may be inviting major ones. But to punish the offender, you'll probably need an eyewitness or a video image.

If the problem is in your warehouse or factory, your best bet is to talk to the manager. Ask that person: have you noticed anything unusual? Even if the manager is involved, that may stop him or her cold. You can also turn to other employees for help, by setting up a hot line for anonymous tips. Cost: from $500 to $25,000 a year.

If inside information isn't turning anything up, maybe it's time to call in an outsider. For about $1,000 a day -- and most small companies require just one day -- a security consultant will cast a trained eye on areas in which security gaps often exist. By day's end, that person should be able to pinpoint your company's most vulnerable spots.

But catching the thief may require still more digging. For about $400 a day, you can send a private investigator into your company dressed as, say, an electrician. If a day or two isn't enough, an investigator can infiltrate the company disguised as a new hire. Beware, though: it may take as long as three months before the veterans let the new kid in on the scam. At $50 an hour, you could lose more money to the investigator than you would to the thieves.