Real estate agents Helen Sotiriadis, 49, and her daughter Irene Sotiriadis, 23, stand accused of a crime that not long ago was so common as to be an industry staple.

Federal and county authorities say the women — who since Sept. 20 have been under house arrest at home in Manteca — overstated the income of 25 Cambodian immigrants to get them approved for expensive variable-rate loans and into 30 upscale homes around Stockton, Tracy and Modesto between 2006 and 2007.

It’s an alleged scheme that cost lenders $5 million. If the allegations eventually translate to convictions, it could land each woman 20 years in prison and a $250,000 fine.

But the criminal charges have led some to question why authorities targeted the Sotiriadis women over other local lenders, a vast number of whom secured clients through the same illegal device, which, since the crash of the housing market, has come to be called a “liar loan.”

Assistant U.S. Attorney Benjamin B. Wagner said it’s simple: Falsified loans are always criminal, but authorities only have so much time and resources to chase down offenders.

Generally, to decide which cases to prosecute, authorities consider “the scope and duration of the criminal activity, the amount of economic harm caused by the conduct, the strength of the evidence, and the history and characteristics of the subjects,” said Wagner, whose federal jurisdiction extends across 34 counties from the Oregon border south to Bakersfield.

In other words, crooked real estate agents were so common that to get targeted for prosecution, lenders and agents had to go the extra mile in duping buyers.

“When I started out, everyone was doing that, those stated-income loans,” said Susan Wilson, who sells homes for Corral Hollow Real Estate in Tracy. “It’s really discouraging, because no one does them now, but the same people who did them are still selling homes.”

She said that realization makes her consider leaving the business.

“I just don’t want to be in a line of work where things like that could happen — where peoples’ lives are falling apart because of this industry,” she said.

What made the Sotiriadis women prime targets for federal agents is that investigators believe the two not only swindled lenders by getting them to issue loans to folks who couldn’t afford them, but also promised buyers to rest assured that they would refinance to payments of $1,500 a month after a one-time payment of $4,000.

Authorities charge that the women took the $4,000 from many clients but never delivered a refinanced loan — and, in most cases, never talked to the clients again.

Calls to Helen Sotiriadis’ cell phone number, provided by employees at her office Royal Mortgage & Real Estate in Manteca, were not immediately returned.

The Sotiriadis women were hardly industry veterans. The two forayed into the home-selling business at Signature Financial in Tracy near the height of the market — a time when the types of loans they’re in trouble for were pretty common.

“When we started out, that’s what we were taught,” Wilson said. “Even the veterans, with decades behind them, said this is the way to do it. No one said it was wrong — and when you’re new, how do you know?”

In fact, victims of brokers and agents who helped people procure homes they couldn’t afford wonder why the people who misled them are still free.

“It’s like business as usual,” Wilson said. “I wonder when, or if, it’s going to catch up with them.”

That’s what Jackie Sylvia of Tracy wonders every day since she lost her home to foreclosure this year — a home she bought thanks to help from a still-in-business agent who guided her to overstate her income on the loan papers.

“While these people are still free,” she said, “I lost my freedom, and my home.”