By CATHARINE SKIPP and DAMIEN CAVE

NORTH LAUDERDALE, Florida ? Mark Guerette, a mortgage broker, has found foreclosed homes for several needy families here in Broward County. There is just one problem: Mr. Guerette is not the owner.

Yet. In a sign of the odd ingenuity that has grown from the real estate collapse, he is depending on an 1869 Florida statute that says properties he has seized will be his if the owners do not claim them within seven years. Mr. Guerette, 47, sees his efforts as heroic. “There are all these properties out there that could be used for good,” he said. But the authorities see him as a crook.

He is scheduled to go on trial in December on fraud charges in a case that could determine whether maintaining a property and paying taxes on it is enough to lead to ownership. Legal scholars say the concept is rooted in Renaissance England, when agricultural land would sometimes go fallow, left untended by long-lost heirs.

All 50 states allow for so-called adverse possession. The statute generally requires paying property taxes and utility bills. Lawyers are seeing such cases all over America.

In Florida, the Sunshine State, many residents have grown accustomed to living beside a home left vacant for years. Now hundreds of these mold-filled houses are being claimed by strangers. “There are all kinds of ways the people try to manipulate the system to their own financial gain,” said Jack McCabe, an independent real estate analyst with McCabe Research and Consulting.

“And you are going to see it here because Florida is the capital of real estate fraud.” Mr. Guerette, who faces up to 15 years in prison, insists that his business is legitimate and moral. He filed court claims on around 100 deserted properties.

Then he chose 20 that could most easily be renovated and sent letters to the owners and their banks to make them aware of his plans. Nineteen of the owners and their banks did not respond, he said. So he fixed up the properties. In some cases, he let tenants make improvements in lieu of rent. At his peak last year, he said he managed 17 homes with renters.

Copies of leases show Mr. Guerette included an addendum noting that he was not the legal owner. Tenants like Fabian Ferguson, who with his wife and two children had been homeless before moving in and paying $289 a month, see Mr. Guerette as a savior.

And neighbors generally agree. “I like them,” said Rawle Thomas, who lives next door, “and I’d much rather have someone in there than the house empty.” In other cases, adverse possession has been more problematic.

In Palm Beach County, Carl Heflin spent a year in jail awaiting trial on fraud, trespassing and burglary charges. But after accepting a plea agreement and the rejection of his adverse possession claims, he was arrested again on charges of trying to collect back rents on houses.

Misty Hall, who rented a home from Mr. Heflin, said that he “threatened to burn the house down with my kids in it.” Sam Goren, city attorney for North Lauderdale, said any benefits were outweighed by a simple fact: possessors are trespassing.

Mr. Guerette says that after several marriages and some minor trouble with the law, he is now a born-again Christian who sees his new company as a way to make an honest living, and solve a dire need. “There are over 4,000 homeless in Broward, and the number is growing all the time,” he said. “I thought I could use these homes and put people into them. It could be a good thing.”