Former homeowners may still be on the hook if there's a difference between what they owed on their mortgage and what the bank could sell it for at auction. And these "deficiency judgments" are ticking time bombs that can explode years after borrowers lose their homes.

It can even happen to people who got their bank to approve them selling their home for less than it is worth.

Vanessa Corey, for example, short sold her Fredericksburg, Va., home in April 2008. She and her husband built the house in 2004, but setbacks, both personal (divorce) and professional (housing bust), made it impossible for the real estate agent to keep her home. So she negotiated the short sale and thought that was the end of it.

"My understanding was that the deficiency was negotiated away," she said. "Then, last November, I got a letter from a lawyer telling me I owed my lender $65,000. I had to declare bankruptcy. There was no way I could pay it."

Where the foreclosure plague is spreading
Many homeowners are now in the same boat. And not just those who took out bigger loans than they could afford or who did so called "liar loans" where they didn't have to verify their income.

Because of falling home prices, borrowers who always paid their mortgage but who have run into unforeseen circumstances -- like unemployment or a job transfer -- can no longer sell their homes for what they owe. As a result, they are being forced to short sell or foreclose and are getting caught up in deficiency judgments.

"After the banks foreclose, it's very common now to have large deficiencies with houses not worth the balances owed," said Don Lampe, a North Carolina real estate attorney.

Lenders mostly declined comment. Although Corey's lender, BB&T did indicate it was pursuing more deficiency judgments.

"They follow the rise and fall of foreclosures," said the spokeswoman, who would not discuss Corey's account.

Can they come after you?
Whether banks can and will pursue deficiency judgments depends on many factors, including what state the borrower lives in and whether there's a second mortgage or other liens. But if borrowers ignore the possibility of deficiencies, it could haunt them.

"Once they have a judgment, they can pursue you anywhere," said Richard Zaretsky, a board-certified real estate attorney in West Palm Beach, Fla. "They can ask for financial records, have your wages garnished and, if you fail to respond, a judge can put you in jail."

In the case of foreclosure, lenders can pursue deficiencies in more than 30 states, including Florida, New York and Texas, according to the U.S. Foreclosure Network, an organization of mortgage law firms.

Some states, such as California, are "non-recourse" and don't allow deficiency judgments. But, even there, if the if the original loan was refinanced, some or all of it may be subject to claims.