When a home buyer has a high credit score, is self-employed with an annual income of more than $100,000, owns a few rental properties, is buying a house priced well above the area average and is buying it alone, what comes to mind?

Solid citizen? A good addition to the neighborhood? An excellent bet to get a big mortgage with a great rate? Sure.

But would you believe fraud? Would you believe that statistically the buyer with that profile is more likely than other loan applicants to be involved in some form of mortgage rip-off skullduggery when the lender he is applying to specializes in loans for home buyers with imperfect credit?

Welcome to the booming world of mortgage fraud. With larceny in their hearts and sophisticated electronic document-preparation programs in their laptops, unethical mortgage loan officers, brokers, real estate agents and lawyers can create fake credit scores, tax returns and identities, as well as ordering inflated appraisals.

According to witnesses at a congressional hearing this month, mortgage fraud is now one of the hottest con games going.

An FBI assistant director testified that fraud is "pervasive" in the mortgage market and is growing fast. Rep. Robert W. Ney (R-Ohio), chairman of the House Financial Services Committee's housing and community opportunity subcommittee, cited industry studies suggesting that "between 10 and 15 percent of all home loan applications involve some fraud or misrepresentation." The potential costs, to buyers and lenders, could be in the billions of dollars a year.

Some of the fraud may seem minor -- a little fibbing on the application about a borrower's income, or a lack of candor about where the buyer's down payment cash really came from. Other fraud is far more organized.

Frequently, mortgage fraud ends up hurting not only lenders but also innocent consumers, witnesses told the hearing. Marta McCall, senior vice president of San Diego-based American Mortgage Network, cited the example of a first-time buyer who was persuaded to purchase a property that was significantly overvalued because of a fraudulent appraisal. The seller pocketed big profit, but now the buyer finds herself unable to refinance and unable to pay off her loan by selling the house because the property is worth less than the mortgage amount.

Faced with more fraud than ever before, lenders nationwide are adopting defensive tactics to sniff out con jobs before they succeed. In one instance described at the hearing, a large national lender has developed its own risk alert system based on extensive statistical analysis of red flags associated with documented cases of fraud. HSBC Mortgage Services Inc., of Prospect Heights, Ill., which specializes in loans to borrowers with credit problems, uses its proprietary FraudScore on all its new mortgages. Some of the red flags are counterintuitive.

For example, said Loren J. Morris, HSBC senior vice president, unusually high credit scores combined with high incomes and higher-than-average mortgage amounts and home values for the neighborhood are among the key telltale signs of fraud in applications. That may sound strange because all these characteristics would normally be associated with cream-puff, problem-free applicants.

The bad guys know this too, and they often try to make a loan application "look as good as possible, so it will sail though" automated underwriting systems without a hitch, Morris said in an interview. Other red flags: self-employed, single people who are buying a home but say they own one or more rental houses.

HSBC's FraudScore system weights these and other factors, including city and state, on a scale of zero to 52. When an applicant presents combined factor weights exceeding a score of 30, an alarm goes off and the company's fraud investigation procedures kick in.

So, what does this mean for home buyers and borrowers who harbor no fraud in their hearts? First, be aware that mortgage cons are rapidly on the rise. Not all appraisers or loan officers you encounter are necessarily playing the game straight. Though they often target big lenders, con artists frequently harm innocent purchasers who end up with loans they don't want, can't afford and can't get rid of. Worse yet, if lenders keep losing millions of dollars to fraud, they're going to pass along those costs to all borrowers in the form of higher fees and interest rates.

Kenneth R. Harney's e-mail address is KenHarney@earthlink.net.