WASHINGTON (CNN) -- The U.S. government announced criminal charges on Tuesday against 530 people as part of a crackdown on mortgage fraud schemes that targeted the most distressed homeowners and caused more than $1 billion in losses.

Attorney General Eric Holder and several other officials said the year-long effort that was launched by the FBI and ended in September was aimed at those preying on people in danger of losing their homes to foreclosure.

"These comprehensive efforts represent an historic, government-wide commitment to eradicating mortgage fraud and related offenses across the country," Holder said at a news conference.

More than 73,000 homeowners nationwide had been victimized by fraud schemes, the government said. Law enforcement estimated the losses at more than $1 billion.

Schemes often involve con-artists who promise homeowners that foreclosure can be avoided, for a fee, by having "investors" purchase their mortgage or by transferring title to an entity involved with the fraud.

FBI Assistant Director Kevin Perkins said many cases were concentrated in Southern California. Last month, 11 people were indicted for their alleged roles in a loan modification scheme that victimized more than 4,000 people. Many of them lost their homes to foreclosure.

U.S. home foreclosures spiked during the recession due to the credit crisis, worsening unemployment and plummeting property values.

Perkins said authorities can sometimes help homeowners get back "some" of their money, but lost homes are seldom recovered due to legal complexities.