From a Department of Homeland Security press release (link):

Immigration and Customs Enforcement have reached a non-prosecution agreement to resolve an investigation with respect to the hiring and employment of unauthorized aliens at Pilgrim's Pride's plants in the Eastern District of Texas... Under the terms of the agreement, Pilgrim's Pride agrees to pay $4.5 million [NOTE: over three years] and adopt more stringent immigration compliance practices to ensure that its work force is composed of employees legally entitled to work in the United States. In return, the U. S. Attorney's Office agrees to conclude its immigration-related investigation of Pilgrim's Pride and any current or former employees... "This case demonstrates that the government and business, working together, can go a long way to resolving the issue of employment of illegal aliens," said U.S. Attorney Bales. "Pilgrim's Pride has cooperated with the United States during this investigation and acknowledged the company's desire to implement rigorous standards to comply with immigration-related laws. With this agreement, Pilgrim's Pride sets itself up as an industry leader in adopting recommended immigration practices. I commend the thorough investigation by Immigration and Customs Enforcement, without which this agreement would not have been possible," Bales said... "ICE's goal is to reduce the opportunity for illegal work in the United States," said John Morton, Department of Homeland Security Assistant Secretary for ICE. "This settlement acknowledges that Pilgrim's Pride is committed to adopting a rigorous immigration compliance program."

For the backstory, see the other entries on the Pilgrims Pride page.