The FBI said in an annual report that pending investigations increased 12 percent in the fiscal year ended Sept. 30, 2010, to 3,129 cases. That in turn was a 90 percent jump from the previous fiscal year.
An FBI official said the trend will continue as more borrowers struggle to pay their mortgages.
``If we have continuing high unemployment and increased numbers of foreclosures, what we see is a greater percentage of the population of existing homeowners being vulnerable to these schemes,'' saidDavid Cardona, FBI deputy assistant director.
The collapse of the housing boom and the resulting financial crisis has led to a wave of foreclosures. In 2010, 2.5 million foreclosures were initiated, with a similar number expected this year.
The FBI said mortgage origination schemes have declined due to the depressed market for home purchases.
Fraud targeting troubled borrowers, however, has increased and includes loan modification scams and foreclosure rescue schemes in which perpetrators convince borrowers they can save their homes through deed transfers and upfront fees.
Cardona said stock market fluctuations have also resulted in more Americans falling for fake investments.
``It's not a dynamic that we think will self-correct. If anything it could get worse,'' he said
The report listed ``hot spots'' for mortgage fraud. California, Florida and New York were among the hottest of those, in line with some of the worst unemployment and mortgage default rates in the country.
Since the FBI was tasked with rooting out criminal activity that exacerbated the housing crisis in 2008, it has been criticized as ineffective against powerful executives of companies tied to the housing and financial industry.
``Although we tried mightily we just didn't hit the mark,'' Cardona said, referring to the aborted investigation of Washington Mutual Bank in early August.
Cardona said the government struggles to prove criminal intent in corporate crime.
One of the biggest cases so far was a $3 billion fraud case involving the privately held mortgage firm Taylor, Bean & Whitaker Mortgage Corp. The chairman of the firm, Lee Farkas, was sentenced to 30 years in prison after being convicted on 14 counts of conspiracy, wire, securities and bank fraud.
Cardona said the FBI is hoping the government can win more high-profile cases through civil probes. He said the FBI is cooperating ``closer now than ever'' with the Securities and Exchange Commission andCommodity Futures Trading Commission.
``We're going to see a quicker return on investment through civil means than showing criminal intent by some of these high-level officials,'' he said.