Ask these questions face-to-face so you can judge the response.
You can judge a person's character by how they answer your questions. If they avoid answering a question, that can say a lot.

When you call references, try to get beyond the usual "he was a good worker" clichés. You might ask if the employer ever had an argument with the employee, what it was about and how it was resolved, for example. Asking open-ended questions, rather than those that can be answered "yes" or "no," can encourage the reference to talk and perhaps reveal more about the worker's character.

Conduct background searches
Trying to do a reasonably thorough background check is beyond the expertise and patience of most people. Fortunately, you can hire an online firm to do a basic search for $40 to $100, or a private investigator for $150 and up. The cost mounts the more databases and details you want checked.

You shouldn't try to do these checks on the sly. The Fair Credit Reporting Act requires employers to get a signed release form from potential applicants before commissioning a background search; reputable firms will ask for one.

Make sure you find a firm that's been in business for several years and has a clean history with the Better Business Bureau. If you want to hire a private eye, you might ask the best nanny agency in your town about who they use.

Also understand that there's no guarantee a background search will turn up every suspicious item in your applicant's past. Not all court and criminal records are available online, and some people are very good at masquerading as others.

But the following searches should help you uncover most of the bad guys:

• Social Security number trace. This will turn up names associated with the number and where those associated with it have lived.
•  Criminal records. Some search firms promise "national" checks, but there is no publicly available database that includes all criminal records. Most records will show up on the county level, so you'll need to know the counties where your applicant has lived in the past 10 years or so and ask the search firm to check each one. (You can cut down on the cost by visiting one or more of the county courthouses yourself, but that's exactly the kind of time-consuming research most people who hire search firms are trying to avoid.)
• Sex-offender databases. This is something you may be able to do yourself, since most states post this information online. You also might check if any sex offenders are registered at your applicant's address; your nanny might be fine, but her husband could be a predator.
• Department of Motor Vehicles records. If the applicant will be driving members of your family, you'll want to know about any offenses that indicate dangerous driving habits.
• Credit check. Employers typically run these when a worker would be in a position of trust, said employment attorney Karol Pollock, on the notion that someone with troubled finances may be more tempted to steal.

You shouldn't accept credit reports at face value, since many contain errors and others reflect financial setbacks that have since been cleared up. That's why you'll want to ask the applicant questions about any black marks you find. I know one nanny whose credit history was besmirched by a friend who convinced her to co-sign a loan then failed to make the payments. It was financially naïve of the nanny to agree to co-sign, but hardly reason not to hire her.Properly weigh the details

Other considerations you should take into account: Federal law prohibits employers from firing, failing to hire or failing to promote someone solely because of a bankruptcy filing.

Legitimate consumer disputes can turn into collections. Some phone companies, hospitals and fitness clubs are notorious for swiftly turning unpaid bills over to collection actions, even when the consumer is in the right.Unpaid medical bills, by themselves, may not be a sign the applicant is a deadbeat. Remember that 45 million Americans are uninsured, and many are underinsured. One accident or illness can result in huge, unpayable medical bills.

What may be more telling are high balances, late payments and defaults on a number of credit cards and other accounts, showing the applicant may be deeply in debt. Serious signs of financial trouble, such as foreclosures, repossessions and tax liens, need an explanation as well.

The result of your investigations should help put your mind at ease, but you may still want to take certain precautions after you've hired your household worker. Locking up checkbooks and private financial files is a good idea; so is dropping in unannounced if you aren't usually at home to supervise. Some household employers even repeat background checks occasionally, to make sure new problems haven't arisen. Trust, but verify.