The officials said the government believed that Wal-Mart executives knew the cleaning contractors were using illegal immigrants.

Government officials and Walmart executives declined yesterday to name the cleaning contractors whose employees were arrested.

A former cleaning contractor and a former high school principal jointly teach sculpture.

Company officials deny having known that illegal immigrants worked in their stores, saying they required their cleaning contractors to use only legal workers.

Wal-Mart is not the only retailer to use questionable cleaning contractors.

So far, 27 master contracts have been made with commercial cleaning contractors across the country.

Her immediate dream is a job that pays more than the $6.50 an hour she earns working for a nonunion cleaning contractor.

Those janitors asserted that they worked seven nights a week and received just $3.50 an hour from the supermarkets' cleaning contractors.

Building One, the cleaning contractor, eventually raised his pay to $320 a week, slightly more than the minimum wage, but with no premium for overtime.

They had said they were not joint employers along with the cleaning contractor.