Last February, Pavel responded to an intriguing Web site that boasted of cleaning jobs in the United States paying four times what he was earning as a restaurant manager in the Czech Republic. He flew from Prague to New York on a tourist visa and took a bus to Lynchburg, Va., where a subcontractor delivered him to a giant Wal-Mart.

Pavel immediately began on the midnight shift and said he soon learned that he would never receive a night off. He said he worked every night for the next eight months. In this way, Pavel, who refused to give his last name, became one pawn among hundreds employed by subcontractors that clean Wal-Mart stores across the nation, paying many workers off the books.

Pavel's unhappy stay in the United States ended with a shock when federal agents raided 60 Wal-Marts on Oct. 23 and arrested him and 250 other janitors as being illegal immigrants.

Here's more about Wal-Mart:

Many people, from janitors to federal investigators, said Wal-Mart store managers and officials at headquarters knew about widespread use of cleaners who are illegal immigrants. "The chief manager of our store knew what was going on," Pavel said. "He knew that we were illegal."

Federal law enforcement officials who spoke on condition of anonymity said Wal-Mart executives must have known about the use of illegal immigrants partly because 13 Wal-Mart cleaning subcontractors pleaded guilty to illegal hiring practices several years ago.

From one of the other undocumented workers:

"When I talk on the phone to friends in Mexico, they ask me how the pay is, and I say, `We're getting $350 a week,' " said Mr. Zavala, a native of Mexico City who was rounded up in the Oct. 23 raid. "They say, `Wow, in Mexico we're earning 300 pesos a week.' That's just $30 a week. So compared with Mexico, it's good money."

Mr. Zavala said it was unjust to deport immigrants who worked hard and well. "We were proud of what we were doing," he said. "Every morning we looked back at the floors, and they looked real shiny. I don't want to get too emotional, but do you think we want to go back to our country and earn just $30 a week?"

One more:

Denis, who refused to give his last name, said he got a medical degree in Russia before taking a job at a Wal-Mart in Lexington, Va. He said the store manager knew that illegal immigrants were cleaning the floors. "It's obvious," he said. "They knew the whole crew consists of foreigners who don't speak English." Denis said it was exhausting to work seven nights a week, with just a 15-minute break. "There were no benefits, no health insurance, no nothing," he said.