A new wave of mortgage fraud cases, in which brokers allegedly purchase identities from immigrants, has mortgage lenders taking a more proactive role in law enforcement, FBI officials said.

Last week, the FBI arrested 10 people with ties to a Bangladeshi community in Queens who allegedly conspired to create a pyramid scheme in which they purchased the identities of immigrants who were leaving New York to move back to Bangladesh, according to FBI officials. The price was usually about $5,000, the officials said.

The agency has charged three principals in a brokerage group, New Generation Funding, with using the purchased identities as “straw buyers” to obtain financing for the purchase of homes. By selling the properties among the “straw buyers,” and raising their value through fraudulently inflated appraisals, the defendants were allegedly able to pocket about $100,000 on each property.

“In the mortgage industry, there is an incentive to get the loan through,” a supervisor in the FBI’s white-collar crime program, Ben Berry, said. “On the way, there is only a small incentive to uncover the fraud.”

Because the mortgages were issued in the names of the “straw buyers,” who in fact had left America, lenders who foreclosed on the mortgaged homes could realize only the properties’ foreclosure value. The scheme netted the alleged conspirators more than $7 million from lenders, a spokesman for the FBI, James Margolin, said. The lenders involved were identified in a federal complaint as Lehman Brothers Holdings Inc., HSBC Holdings Plc., and Fremont General Corp.

Mr. Berry said his office is hopeful about bringing charges in a similar mortgage fraud case this week. Over the past few years, the FBI and other law enforcement officials have dismantled several similar schemes, according to court records. A mortgage broker in Queens, Larry Stathakis, was recently convicted of using stolen identities as straw buyers to scam large mortgage lenders, such as ABN Amro and Fleet Bank, over about a four-year period, according to his indictment in U.S District Court.

The case of the New Generation defendants, however, adds a twist to the alleged mortgage fraud conspiracies. In what Mr. Berry called a “cutting edge” tactic, the brokers at New Generation Funding allegedly used their connections in the Bangladeshi community to purchase identities from people who had built-up authentic credit, leaving the lenders as the only victims.

“These types of crimes are insidious because you’re not talking about stolen identities,” Mr. Berry said.

However, it was the lenders who prodded the FBI to investigate the New Generation Funding mortgage brokerage after they noticed a high rate of loan foreclosures in late 2005, Mr. Berry said.

Spokesmen for Lehman Brothers Holdings Inc., HSBC Holdings Plc., and Fremont General Corp. declined to comment on their companies’ roles in the investigation.

Corporations are becoming more inclined to investigate mortgage fraud as the epidemic grows, Mr. Berry said. FBI mortgage fraud investigations have risen to 938 in January of this year from 721 in September 2005, an FBI mortgage-fraud investigations coordinator, William Stern, told the New York Times earlier this year.

One way that lenders can combat this type of fraud is by insisting that their own appraiser decide the value of a property, a real estate lawyer at Ganfer & Shore LLP, Steven Ganfer, said.