Robert Philip Hanssen passed background checks for 15 years before the FBI accused him of being a mole this week.

While most of us will never face treason charges because of slip-ups in our pasts, having skeletons in your closet could come back to haunt you in your present job - or affect your future career aspirations, experts say.

Many job seekers have something in their past that could come back to haunt them. Anything from fudging details on resumes, to rounding up GPA averages, to having bad credit records might become a major career liability if discovered by an employer.

One manager at a major financial management company says it's disappointingly common to catch people in lies - and to have to rescind offers of employment as a result.

"Most people lie about their background, their GPA in college, their position at their former [or] current company, their responsibilities, their salary," she says. "The most surprising are college students who lie about their GPAs and academic achievements. They have to know that we are going to request their transcript and find out the truth!"

More often than not, a job candidate's secrets are uncovered through the reference checking process, says Terra Dourlain, managing director of Allison & Taylor Reference. The Jamestown, N.Y. employment verification and reference-checking service is used by job hunters both to overcome bad or mediocre references, or sometimes to find out who their biggest boosters are.

"It's not so cloak and dagger," she says. "In the real world it's actually talk [that leads to trouble.]"

Some 86 percent of businesses surveyed require applicants to sign waivers allowing them to check references and former employers, according to a 1998 survey by the Society for Human Resource Management. On average, 2.7 references are called about the candidate.

~ Increasingly, companies are turning to background-checking companies to pull out information on prospective employees from public records, such as motor vehicle reports, credit reports, workers compensation and criminal records. The background check industry is a $200 million market that's growing at a 30 percent rate per year, according to Avert Inc., a Colorado-based employment selection and screening services provider.

Thirty percent of resumes and work references conflict with past employer statements, and seven percent of job seekers have criminal records, according to Avert. Among applicants checked by Avert in 1999, 12 percent had four or more moving violations, two or more accidents, a DUI or DWI, or had a suspended driver's license. Some 25 percent had one or more public records on their credit report including judgment, lien or bankruptcy, or had been turned over to a collection agency. Avert counts 14,000 companies, both big and small, among clients.

White-collar firms are particularly interested in an applicant's credit history report, says Gary Hanley, vice president of USA-FACT Inc., a Riverside, Calif.-based employment screening company. "They want to see how you manage your own money before you manage theirs," says Hanley. "What they are looking for out of these reports is how responsible you are as an individual.

"The higher the position, the more intense the screening," he adds.

If you do have nagging secrets, none of this is good news. But there are ways to silence the rattle of the skeletons in your closet.

"The reality is that if you have a criminal record and a company runs a background check, it's going to come up. And if you have bad credit and they run a credit check, it's going to come up," says Dourlain. "Depending on your position, they may or may not be able to hold it against you."

If you're in a financial job, bad credit will plague you. But if you're in another field, your former money misdeeds may or may not cause you employment problems. The question is how you spin the situation.

~ "[Bad credit can be] another reason why they won't hire you," adds Dourlain. "Since pretty much they're going to find it out, you have to turn it around. That's your biggest challenge."

In such a case, she says, you should try to turn your negative into a positive. If your credit came at a time when the rest of your life was falling apart, this might work: "I went through a terrible divorce, it cost me a lot, including my credit," she says. "But I stuck to my guns, got my career under control and now I'm digging my way out."

Another important self-defense tactic is to learn what your former employees, including references, are saying about you.

Many companies have policies stating that they will only release basic information such as the verification of titles and dates of employment and whether or not you are eligible for rehire. However, a reference check is a private conversation between two people - your past employer and a prospective one, she points out. If your former boss is damaging your reputation, you may be able to put a stop to it either through legal means or simply by calling him with proof of his illegal remarks.

"A negative reference is only legal as long as it is the truth and it can be proven or documented," she says.

Alison & Taylor has supplied its research evidence and testified in support of ex-employees done wrong.

Sometimes learning what references say will save you from having to talk about your past troubles. She recalls one client who was fired for embezzling money. In time, he tried starting his life over but was having no luck finding a company sympathetic to reformed embezzlers, she says.

When he learned that the company he stole from only gave the briefest of information about his job tenure, including the duration of his stay and title, he stopped talking about the whole ugly affair.

"The only way other companies found out was by him," Dourlain says. "He didn't have a criminal record and he was paying the company back. Here was a guy owning up to his past and he was actually hurting himself."

Another client was fired from a banking position two years after taking a job for lying about his GPA, Dourlain says. He wasn't sure he would ever get a job again until he used Alison & Taylor to learn that his old company only reveals the dates of his employment and titles.

"He will never lie again," she says.