Federal authorities charged that a methamphetamine laboratory was operating at the nation's largest kosher slaughterhouse and that employees carried weapons to work.
The charges were among the most explosive details to emerge following the massive raid Monday at Agriprocessors in Postville, Iowa.
In a 60-page application for a search warrant, federal agents revealed details of their six-month probe of Agriprocessors. The investigation involved 12 federal agencies, including the Drug Enforcement Administration, the Federal Bureau of Investigation and the departments of labor and agriculture.
According to the application, a former plant supervisor told investigators that some 80 percent of the workforce was illegal. They included rabbis responsible for kosher supervision, who the source believed entered the United States from Canada without proper immigration documents. The source did not provide evidence for his suspicion about the rabbis.
The source also claimed to have confronted a human resources manager with Social Security cards from three employees that had the same number. The manager laughed when the matter was raised, the source said.
At least 300 people were arrested Monday during the raid, for which federal authorities had rented an expansive fairground nearby to serve as a processing center for detainees.
The search warrant application said that 697 plant employees were believed to have violated federal laws.
Agriprocessors officials did not return calls from JTA seeking comment.