For American homeowners drowning in mortgage and consumer credit debt, here is a grim warning from law-enforcement agencies: There are sharks in the water.

* On Monday, Missouri Attorney General Jay Nixon announced "Operation Stealing Home" to crack down on mortgage fraud and financial predators taking advantage of homeowners facing foreclosure. Nixon's office filed lawsuits against seven individuals and businesses accused of defrauding customers through refinancing, advance fee and foreclosure consulting scams.

* In May, a national alert against foreclosure scams was issued by the U.S. Treasury Department's Office of the Comptroller of the Currency, which charters, regulates and supervises all national banks.

The alert warned against variations of lease-back and repurchase scams that promise financially distressed homeowners they can stay in their homes.

Basically, the schemer offers to pay the mortgage and rent your home back to you. Often, they may promise to sell the home back to you when you've recovered from your troubles. In the meantime, the homeowner is asked to transfer the property deed, often to a third party, who now has the power to sell your house, charge you sky-high rent, evict you and, most likely, steal whatever equity you had in the house. In the meantime, you are still responsible for the mortgage and if the schemer stops making your monthly payments, you still end up in foreclosure.

* Local FBI agents are actively investigating mortgage fraud in the St. Louis area, with the U.S. Attorney's office prosecuting nine cases between March 1 and June 18. "Operation Malicious Mortgage," a national FBI effort during that same time, netted charges against 406 defendants, responsible for $1 billion in fraud. Nationwide, the FBI has 15,000 mortgage fraud cases pending, up from 436 in 2003.

Maxwell Marker, assistant special agent in charge of the FBI's St. Louis division, said that as funding dried up in the mortgage market, schemers began shifting to foreclosure-based scams.

"They'll identify individuals who are in financial distress but have some degree of equity in their property. They essentially make an offer that can't be refused," he said.

Marker said the FBI has seen lease-back schemes in St. Louis but not to the degree that it has occurred in other cities, such as Atlanta, Las Vegas or on the West Coast, where the fallout from the mortgage crisis has been more severe.

The most common form of mortgage fraud in St. Louis is a form of flipping. Schemers purchase run-down properties and then resell them at huge profits, based on fraudulent appraisals claiming rehab work that was never done, said Alan Peak, supervisory special agent of the St. Louis FBI.

"They go into targeted areas and purchase vacant properties for $30,000 or $40,000. Sometimes, in as little as 72 hours, they will sell those properties to a straw buyer they have lined up, in some cases for $130,000 or $140,000 using a fraudulent appraisal report,'' Peak said.

Ultimately, the mortgages are sold on the secondary market and the property ends up in foreclosure again, still in the same run-down condition and still worth only $30,000 or $40,000. In the short term, though, property values in the neighborhood go up, driven by the inflated sales prices. That, in turn, drives up property tax assessments. When the schemers pull out, property values plummet, and the neighborhood is left holding the bag.

"We're all the victims," Marker points out. "It affects every single one of us. It affects us in the fees we pay to get a mortgage. It affects us in our property values. It can affect individuals from $20,000 properties to multimillion-dollar properties. It affects the gamut."

Mortgage fraud can take years to unravel, the agents say. In one of the biggest local cases, the FBI tracked 65 flipped properties to the same group.

Marker said the scammers usually target individuals who are unsophisticated in financial matters, or they work through places of trust, such as churches. They might co-op a church member who will then share his or her good fortune with others. And they are industry-savvy.

"They're very good at exploiting any crack in the system. We'll identify one of those cracks and work with the industry to close it, and they'll move somewhere else," Marker said.

Expect to see the Missouri attorney general's office file more lawsuits against predators, said John Fougere, a spokesman for Nixon. Fougere would not put a number on pending investigations but said announcements of such legal actions often spur other consumers to contact authorities about similar experiences.

Fougere said predators take advantage of flood and tornado victims, so it is not surprising to find them at work during a financial crisis.

Even people who know better can fall for schemes when faced with financial troubles, the FBI agents say.

"When somebody is desperate and they see that life (preserver) ring out there, they'll grab for anything," Marker said.

The agents say they will be watching for new schemes after housing-rescue legislation is signed into law.

"Anytime there's a big pool of money out there, there are bad guys lurking in the shadows trying to figure out how to get their hands on it," Peak said.