CEDAR RAPIDS (AP) — A former manager of a kosher slaughterhouse raided by federal immigration agents in May was arrested Thursday morning.

Sholom Rubashkin was scheduled to make an initial appearance in federal court in Cedar Rapids on Thursday afternoon. Immigration agents arrested Rubashkin, son of company owner Abraham Aaron Rubashkin, in Postville earlier in the day.

The 49-year-old will face charges of conspiracy to harbor undocumented immigrants for financial gain, aiding and abetting document fraud and aiding and abetting aggravated identity theft.

Agents raided the Agriprocessors plant on May 12, arresting 389 people in what officials said at the time was the largest single-site immigration bust in U.S. history.

Telephone messages left for Agriprocessors officials and Rubashkin’s lawyer weren’t immediately returned.

According to the federal affidavit, immigration agents said they seized dozens of fraudulent permanent resident alien cards during the raid at the plant.

It said an unnamed witness, whose responsibilities at the plant included safety orientation for new employees, told agents that he or she had been asked by Rubashkin to train a large number of new employees on the Sunday before the raid, instead of a Tuesday, when training normally took place.

Another witness said he or she was called in to process and hire new employees on the same Sunday. The witness said in the affidavit that he or she noted that a group of applicants had resident alien cards that appeared to be new, but the witness believed the group may have been current employees who were supposed to have been fired the previous Friday.

That witness claimed Rubashkin looked at the IDs and said they “looked good to him.”

Another witness, a former supervisor in the beef kill area, said in the affidavit that he or she met with Rubashkin in a barn area of the plant the week before the raid. The witness told Rubashkin that $4,500 was needed to help employees fired from the witness’ department because they had bad papers. Rubashkin apparently asked if the money had to be in cash and the next morning agreed to loan it. Later in the day another employee gave the witness the cash.

That witness said he or she then gave money to employees to purchase new identification documents. The new documents were obtained and given to up to 40 employees a day before the raid, according to the affidavit.

Earlier this week, Laura Althouse, a human resources employee with Agriprocessors, pleaded guilty to conspiracy to harbor undocumented immigrants for financial gain and aggravated identity theft. Trial is scheduled for Nov. 17 for another human resources worker, Karina Freund.

Two of the plant’s meatpacking supervisors also faced federal immigration charges. Martin De La Rosa-Loera pleaded guilty under an agreement with prosecutors to aiding and abetting the harboring of undocumented immigrants. Juan Carlos Guerrero-Espinoza pleaded guilty to one count of conspiracy to hire illegal immigrants and one count of aiding and abetting the hiring of illegal immigrants.

In September, the owner and managers of the plant, including Sholom Rubashkin, were charged with 9,311 misdemeanors alleging they illegally hired minors and let children younger than 16 handle dangerous equipment. The complaint filed by the Iowa attorney general’s office said the violations involved 32 illegal-immigrant children younger than 18, including seven who were not yet 16.