The Lee County Sheriff's Office arrested a dozen workers at Iowa Fertilizer Company's plant near Wever for identity theft on Thursday.
Sheriff Jim Sholl says his office received an anonymous tip about the possibility of undocumented workers at the plant.
He says deputies responded to the plant and stopped two school buses that were transporting Spanish-speaking workers to a special safety meeting.
"We simply checked the documents for all those workers. 12 are in custody out of more than 40 but less than 50 persons (that were on the buses)."
Sholl says the twelve had assumed other identities so their paperwork matched up with the social security numbers they had stolen.
He says Iowa Fertilizer Company is a victim in this because the method used would not have shown up on background checks.
Sholl says the twelve are currently being housed in the Lee County Jail. He says the amount of money they earned while using a stolen identity will determine their possible penalty.
Sholl says it appears they worked for two subcontractors.
He says U.S. Immigration and Customs Enforcement responded to the scene to help with the language barrier, but he does not know if the agency will pursue federal charges.
Sholl says this case will be handled just like it would if the identity of a Lee County resident had been stolen.
President Shawn Rana said in a brief statement that Iowa Fertilizer Company works with the appropriate federal and state regulatory agencies on hiring practices.