Orson Benn, once a vice president at the nations largest subprime lender, spent three years during the height of the housing boom tutoring Florida mortgage brokers in the art of fraud.

From his office in New York, he taught them how to doctor credit reports, coached them to inflate income on loan applications, and helped them invent phantom jobs for borrowers.

When trouble arose -- one broker got caught, another got cold feet -- Benn called his trusted fixer in Miami to remove the problem and get the loan approved: Yvette Valdez.

The 48-year-old Valdez was a key figure in helping Benn tap into one of the country's most lucrative mortgage markets during his run with Argent Mortgage, The Miami Herald found.

Benn and several associates were convicted of racketeering this year, but Valdez still sells mortgages from a nondescript storefront in Homestead.

While prosecutors looked at roughly $100 million in loans written by Benn and a cadre of co-workers, that represents just a portion of the loans they approved during his aggressive expansion into Florida.

The Miami Herald found that Benn's network approved more than $550 million in home loans from Tampa to West Palm Beach to Miami, according to an analysis of court records.

In Miami-Dade County alone, Benn's office approved more than $349 million in loans on 1,913 homes -- more than one in three have since fallen into foreclosure, the analysis shows.

Valdez brokered at least 100 of those loans worth $22 million -- nearly all based on false and misleading financial information, the newspaper found.

One borrower claimed to work for a company that didn't exist -- and got a $170,000 loan. Another borrower claimed to work a job that didn't exist -- and got enough money to buy four houses.

In a brief interview with The Miami Herald, Valdez blamed the borrowers, refusing to comment further. Her lawyer, Glenn Kritzer, said she has done nothing illegal.

With so many of Benn's loans now in foreclosure, Miami-Dade County is littered with still more empty homes. Squatters inhabit some; crack dens occupy others. At least one has been stripped to the ground, leaving only the foundation.

"It's like a desert, " said Reynaldo Perez, 41, who lives in a Homestead town house financed by Benn three years ago. "Just on my street, there are five or six homes being foreclosed."

Although the Office of Financial Regulation -- the state agency entrusted with policing the mortgage industry -- was alerted to Valdez's role in Benn's network at least three years ago, it never launched an investigation, the newspaper found.

Since 2005, the agency has had copies of some of the same misleading loan applications that The Miami Herald reviewed.

Terry Straub, the OFR's director of finance, acknowledged that his agency had evidence against Valdez. "I don't have any explanation for why we didn't pursue it, " he said.

In fact, state regulators ignored more than a dozen written warnings about brokers in Benn's network, the agency's records show.

Despite a law banning criminals from getting licensed -- created after a Miami Herald series was published this summer -- two brokers in Benn's network who pleaded guilty in May to conspiracy charges in the case remain licensed.

THE BEGINNING

The path to Valdez and other brokers began in 2002, when Benn was hired by Argent Mortgage, which would become the nation's largest provider of loans to people with low credit scores.